The question is ambiguous since it is not clear what the question means.
If there is a mapping such that
t(0) = 1
t(1) = 1
t(2) = 2
t(3) = 6
and you require t(5), then the answer is anynumber. It is easy to find a rule based on a polynomial of order 4 such that the first four numbers are 1, 1, 2 and 6 followed by the chosen next number. There are also non-polynomial solutions. Short of reading the mind of the person who posed the question, there is no way of determining which of the infinitely many solutions is the "correct" one.
Here, fitting the 3rd degree polynomial,
t(n) = (2n^3 - 3n^2 + n + 6)/6 for n = 0, 1, 2, ...
gives t(5) = 31.
How to solve: 3x - 2y = 1 3x2 - 2y2 + 5 = 0 Rearrange the first equation to make x or y the subject (that is x = something or y = something) and then substitute into the second equation and solve that: 3x - 2y = 1 => y = (3x - 1)/2 3x2 - 2y2 + 5 = 0 => 3x2 - 2((3x - 1)/2)2 + 5 = 0 [substitute for y] => 3x2 - 2(9x2 - 6x + 1)/4 + 5 = 0 [expand the square term] => 3x2 - (9x2 - 6x + 1)/2 + 5 = 0 [spot that 2w/4 is the same as w/2] => 6x2 - (9x2 - 6x + 1) + 10 = 0 [multiply equation by 2] => 6x2 - 9x2 + 6x - 1 + 10 = 0 [remove the brackets by multiplying by -1 as it is -1 x (..)] => -3x2 + 6x + 9 = 0 [collect together terms] => 3x2 - 6x - 9 = 0 [multiply whole equation by -1] => x2 - 2x - 3 = 0 [divide whole equation by 3] => (x - 3)(x + 1) =0 [factorize) => x = 3 or -1 [as one factor or the other must be zero] Now use first equation to find corresponding y terms: x = 3:y = (3 x (3) - 1) / 2 = 8 / 2 = 4 x = -1: y= (3 x (-1) - 1) /2 = -4 / 2 = -2 So the solution is the (x, y) pairs, or points, (3, 4) and (-1, -2). The answer can be checked using the second equation: (3, 4): 3(3)2 - 2(4)2 + 5 = 3 x 9 - 2 x 16 + 5 = 27 - 32 + 5 = 0 (-1, -2): 3(-1)2 - 2(-2)2 + 5 = 3 x 1 - 2 x 4 + 5 = 3 - 8 + 5 = 0
Point of contact: (3, 4) Circle equation: x^2 +y^2 -2x -6y+5 = 0 Completing the squares: (x-1)^2 +(y-3)^2 -1 -9 +5 = 0 So: (x-1)^2 +(y-3) = 5 Centre of circle: (1, 3) Slope of radius: (3-4)/(1-3) = 1/2 Slope of tangent: -2 Equation of tangent line: y-4 = -2(x-3) => 2x+y = 10 Tangent line meets the x axis at: (5, 0) Using formula distance from (1, 3) to (5, 0) = 5 units
A Pentagon has 5 angles. It can have 0, 1, 2, 3 or all 5 equal.
If y = -3x - 2 then substituting x from each ordered pair gives :- A) (1,1) y = (-3*1) - 2 = -5 ☒ B) (0,-1) y = (-3*0) - 2 = -2 ☒ C) (0,0) y = (-3*0) - 2 = -2 ☒ D) (-1,0) y = (-3*-1) - 2 = 1 ☒ So the answer is ALL OF THEM are not solutions to the equation y = -3x - 2.......BUT, you've used the word Inequality so depending whether y > -3x - 2 or y < -3x -2 clearly affects the results.
1-1 1-2 1-3 1-4 1-5 1-6 2-1 2-2 2-3 2-4 2-5 2-6 3-1 3-2 3-3 3-4 3-5 3-6 4-1 4-2 4-3 4-4 4-5 4-6 5-1 5-2 5-3 5-4 5-4 5-6 6-1 6-2 6-3 6-4 6-5 6-6 So there ARE 36 possible outcomes, you see. Answer BY: Magda Krysnki (grade sevener) :P
+4 +3 +3 -4 -3 -2 0 -1 +3 +1+1 0 +1
each row has the contents of 8 5 3 in that order 8 0 0 5 0 3 5 3 0 2 3 3 2 5 1 7 0 1 7 1 0 4 1 3 4 4 0 the other solution is 8 0 0 3 5 0 3 2 3 6 2 0 6 0 2 1 5 2 1 4 3 4 4 0 See related link "Dividing" for more info
3. 1 4 1 5 9 2 6 5 3 5 8 9 7 9 3 2 3 8 4 6 2 6 4 3 3 8 3 2 7 9 5 0 2 8 8 4 1 9 7 1 6 9 3 9 9 3 7 5 1 0 5 8 2 0 9 7 4 9 4 4 5 9 2 3 0 7 8 1 6 4 0 6 2 8 6 2 0 8 9 9 8 6 2 8 0 3 4 8 2 5 3 4 2 1 1 7 0 6 7 9 8 2 1 4 8 0 8 6 5 1 3 2 8 2 3 0 6 6 4 7 0 9 3 8 4 4 6 0 9 5 5 0 5 8 2 2 3 1 7 2 5 3 5 9 4 0 8 1 2 8 4 8 1 1 1 7 4 5 0 2 8 4 1 0 2 7 0 1 9 3 8 5 2 1 1 0 5 5 5 9 6 4 4 6 2 2 9 4 8 9 5 4 9 3 0 3 8 1 9 6 4 4 2 8 8 1 0 9 7 5 6 6 5 9 3 3 4 4 6 1 2 8 4 7 5 6 4 8 2 3 3 7 8 6 7 8 3 1 6 5 2 7 1 2 0 1 9 0 9 1 4 5 6 4 8 5 6 6 9 2 3 4 6 0 3 4 8 6 1 0 4 5 4 3 2 6 6 4 8 2 1 3 3 9 3 6 0 7 2 6 0 2 4 9 1 4 1 2 7 3 7 2 4 5 8 7 0 0 6 6 0 6 3 1 5 5 8 8 1 7 4 8 8 1 5 2 0 9 2 0 9 6 2 8 2 9 2 5 4 0 9 1 7 1 5 3 6 4 3 6 7 8 9 2 5 9 0 3 6 0 0 1 1 3 3 0 5 3 0 5 4 8 8 2 0 4 6 6 5 2 1 3 8 4 1 4 6 9 5 1 9 4 1 5 1 1 6 0 9 4 3 3 0 5 7 2 7 0 3 6 5 7 5 9 5 9 1 9 5 3 0 9 2 1 8 6 1 1 7 3 8 1 9 3 2 6 1 1 7 9 3 1 0 5 1 1 8 5 4 8 0 7 4 4 6 2 3 7 9 9 6 2 7 4 9 5 6 7 3 5 1 8 8 5 7 5 2 7 2 4 8 9 1 2 2 7 9 3 8 1 8 3 0 1 1 9 4 9 1 2 9 8 3 3 6 7 3 3 6 2 4 4 0 6 5 6 6 4 3 0 8 6 0 2 1 3 9 4 9 4 6 3 9 5 2 2 4 7 3 7 1 9 0 7 0 2 1 7 9 8 6 0 9 4 3 7 0 2 7 7 0 5 3 9 2 1 7 1 7 6 2 9 3 1 7 6 7 5 2 3 8 4 6 7 4 8 1 8 4 6 7 6 6 9 4 0 5 1 3 2 0 0 0 5 6 8 1 2 7 1 4 5 2 6 3 5 6 0 8 2 7 7 8 5 7 7 1 3 4 2 7 5 7 7 8 9 6 0 9 1 7 3 6 3 7 1 7 8 7 2 1 4 6 8 4 4 0 9 0 1 2 2 4 9 5 3 4 3 0 1 4 6 5 4 9 5 8 5 3 7 1 0 5 0 7 9 2 2 7 9 6 8 9 2 5 8 9 2 3 5 4 2 0 1 9 9 5 6 1 1 2 1 2 9 0 2 1 9 6 0 8 6 4 0 3 4 4 1 8 1 5 9 8 1 3 6 2 9 7 7 4 7 7 1 3 0 9 9 6 0 5 1 8 7 0 7 2 1 1 3 4 9 9 9 9 9 9 8 3 7 2 9 7 8 0 4 9 9 5 1 0 5 9 7 3 1 7 3 2 8 1 6 0 9 6 3 1 8 5 9 5 0 2 4 4 5 9 4 5 5 3 4 6 9 0 8 3 0 2 6 4 2 5 2 2 3 0 8 2 5 3 3 4 4 6 8 5 0 3 5 2 6 1 9 3 1 1 8 8 1 7 1 0 1 0 0 0 3 1 3 7 8 3 8 7 5 2 8 8 6 5 8 7 5 3 3 2 0 8 3 8 1 4 2 0 6 1 7 1 7 7 6 6 9 1 4 7 3 0 3 5 9 8 2 5 3 4 9 0 4 2 8 7 5 5 4 6 8 7 3 1 1 5 9 5 6 2 8 6 3 8 8 2 3 5 3 7 8 7 5 9 3 7 5 1 9 5 7 7 8 1 8 5 7 7 8 0 5 3 2 1 7 1 2 2 6 8 0 6 6 1 3 0 0 1 9 2 7 8 7 6 6 1 1 1 9 5 9 0 9 2 1 6 4 2 0 1 9 8 9
(0 + 1 + 5 + 3 + 3 + 3 + 0 + 2 + 2) / 9 = 2.1 recurring (that is, 2.1111...)
No sorry you can't Actually, you can: 0 - 2 + 3 * 5 = 5 0 - 2 = -2 -2 + 3 = 1 1 * 5 = 5
1 2 0 3 -1 4 -2 5 -3 6 or 1 2 3 4 5 6 ... interlaced with 0 -1 -2 -3 -4 -5 .....
Intro/outro: e-|-7-8-------5-7------------------------| B-|-7-8-------3-5------5-7------8-5------| G-|--------------------2-4---------------| D-|-----------------------------0-2------| A-|--------------------------------------| E-|--------------------------------------| Riff 1: P.M. P.M.... e-|-------------------| B-|-------------------| G-|-------------------| D-|-------------------| A-|-/8-----/8---------| E-|-/6-0-0-/6-0-0-0-0-| Riff 2: P.M e-|-------------------| B-|-------------------| G-|-------------------| D-|-----------2-----5-| A-|-4---2---4-0-4---3-| E-|-2---0---2---2-2---| Add 1: e-|--------| B-|--------| G-|--------| D-|-4------| A-|-4------| E-|-2------| Add 2: e-|-------| B-|-------| G-|-------| D-|-5---4-| A-|-3---2-| E-|-------| Riff 3: P.M P.M....| e-|-------------------| B-|-------------------| G-|-------------------| D-|-/5-----/5---------| A-|-/3-----/3---------| E-|----2-2----2-2-2-2-| Chorus: P.M...........| P.M.........| e-|-----------------------------------------------------------| B-|-----------------------------------------------------------| G-|-----------------------------------------------------------| D-|-6---5-4---6-----------------6---5-4---6-------------------| A-|-4---3-2---4-0-0-0-0-0-0-0-0-4---3-2---4-0-0-0-0-0-0-0-2br-| E-|-----------------------------------------------------------| Riff 4: P.M |.| |.....| |-------| e-|-------------------------------------------------| B-|-------------------------------------------------| G-|-------------------------------------------------| D-|-9\8\7---5-----4---------------------------------| A-|-7\6\5---3-----2-5-----------5-2-----------5-2---| E-|-------0---0-0---3---0-0-0-0-3-0-0-0-0-0-0-3-0---| Riff 5: P.M...| |.........| |.........| |.........| e-|----------------------------------------------------------- B-|----------------------------------------------------------- G-|----------------------------------------------------------- D-|---------5---------------5---------------4---------------4- A-|-4-4-4-4-3---3-3-3-3-3-3-3---3-3-3-3-3-3-2---2-2-2-2-2-2-2- E-|----------------------------------------------------------- P.M.......| |.........| |.........| |.........| --------------------------------------------------------------- --------------------------------------------------------------- --------------------------------------------------------------- -------------3---------------3---------------2---------------2- -2-2-2-2-2-2-1---1-1-1-1-1-1-1---0-0-0-0-0-0-0---0-0-0-0-0-0-0- --------------------------------------------------------------- P.M....| |.........| |..........| |..........| -------------------------------------------------------------| -------------------------------------------------------------| -------------------------------------------------------------| -------------------------------------------------------------| ---------3---------------3---------------5---------------8---| -1-1-1-1-1---1-1-1-1-1-1-1---1-1-3-3-3-3-3---3-3-6-6-6-6-6---| Riff 6: P.M. e-|----------------| B-|----------------| G-|---------5------| D-|-9\8\7---5------| A-|-7\6\5---3------| E-|-------0--------| Add 3: e-|--------| B-|--------| G-|-4------| D-|-4------| A-|-2------| E-|--------| Riff 7: P.M |...| e-|----------------------------------| B-|----------------------------------| G-|-------------5--------------------| D-|-2-----------5--------------------| A-|-2-----------3---3-----5/---7-7---| E-|-0-------0-0-----3-3-3-3/---5-5---| Riff 8: P.M....| |......| |.| |.| |.| e-|----------------------------------------------------------| B-|----------------------------------------------------------| G-|----------------------------------------------------------| D-|-------------7--------------------------------------------| A-|-4-----------5-----------7/---7---7-------7-------7-------| E-|-2---2-2-2-2-----5-5-5-5-5/---5---5---5-5-5---5-5-5---5-5-| Riff 9: e-|----------------------------------------| B-|----------------------------------------| G-|----------------------------------------| D-|----------------------------------------| A-|-7---7---7------5---5------3------------| E-|-5---5---5------3---3------1------------| Riff 10: P.M...................................| e-|-------------------------------------------------------| B-|-------------------------------------------------------| G-|-------------------------------------------------------| D-|-------------------------------------------4---5---4---| A-|---------4-5-----------4-5-----------4-5---2---3---2---| E-|-0-0-0-0-2-3---0-0-0-0-2-3---0-0-0-0-2-3---------------| Riff 11: P.M....| |.........| |.........| |.........| e-|------------------------------------------------------------ B-|------------------------------------------------------------ G-|------------------------------------------------------------ D-|---------5---------------5---------------4---------------4-- A-|-3-3-3-3-3---3-3-3-3-3-3-3---3-3-2-2-2-2-2---2-2-2-2-2-2-2-- E-|------------------------------------------------------------ P.M........| |..........| |.........| |..| ----------------------------------------------------- ----------------------------------------------------- ----------------------------------------------------- -------------3---------------3---------------2------- -2-2-1-1-1-1-1---1-1-1-1-1-1-1---1-1-0-0-0-0-0---0-0- ----------------------------------------------------- P.M.....| |..| -----------------| -----------------| -----------------| ---------2-------| -0-0-0-0-0---0-0-| -----------------| Riff 12: P.M....| P.M........| P.M........| P.M.......| e-|-----------------------------------------------------------| B-|-----------------------------------------------------------| G-|-----------------------------------------------------------| D-|---------10--------------10--------------7---------------8-| A-|-8-8-8-8-8---8-8-8-8-8-8-8---8-8-5-5-5-5-5---5-5-6-6-6-6-6-| E-|-----------------------------------------------------------| Add 4: e-|-------------| B-|-------------| G-|-------------| D-|-5---4---3---| A-|-3---2---1---| E-|-------------| Riff 13: e-|------------------------| B-|------------------------| G-|------------------------| D-|-----------2-----5------| A-|-4---2---4-0-4---3------| E-|-2---0---2---2----------| Riff 14: e-|---------------------| B-|---------------------| G-|---------------------| D-|-----------2---------| A-|-4---2---4-0-4---2---| E-|-2---0---2---2---0---| Riff 15: P.M. |.| |.| |.| e-|-------------------------------------------------------| B-|-------------------------------------------------------| G-|-------------------------------------------------------| D-|-----------2-----5-------5-------5-------5-------5\4---| A-|-4---2---4-0-4---3---3-3-3---3-3-3---3-3-3---3-3-3\2---| E-|-2---0---2---2-----------------------------------------| Add 5: P.M.......... .| e-|-----------------| B-|-----------------| G-|-----------------| D-|-----------------| A-|-----------------| E-|-0-0-0-0-0-0-0-0-| That was all the riffs, lads! This will show you when to play them: Intro x4 Riff 1 x12 Riff 2 x4 Add 1 x1 Add 2 x1 Riff 1 x4 Add 2 x1 Riff 1 x4 Add 2 x1 Riff 3 x4 Chorus x1 Riff 3 x2 Chorus x1 Riff 2 x4 Riff 1 x4 Add 2 x1 Riff 1 x4 Add 2 x1 Riff 3 x4 Chorus x1 Riff 3 x2 Chorus x1 Riff 4 x4 Riff 5 x1 Riff 4 x3 Riff 6 x1 Add 3 x1 Riff 7 x4 Riff 8 x4 Riff 9 x1 Riff 10 x4 Riff 11 x2 Riff 12 x1 Riff 11 x1 Riff 12 x1 Riff 4 x4 Riff 5 x1 Riff 4 x3 Riff 6 x1 Riff 1 x12 Add 4 x1 Add 1 x1 Riff 1 x4 Add 1 x1 Riff 1 x4 Add1 x1 Riff 3 x4 Chorus x1 Riff 3 x2 Chorus x1 Riff 2 x4 Riff 13 x1 Riff 14 x1 Riff 13 x1 Riff 14 x1 Riff 15 x1 Riff 14 x1 Add 5 x1 Riff 15 x1 Riff 14 x1 Add 5 x1 Outro x1
There are 10!/(4!(10-4)!) = 210 such combinations assuming no repeats are allowed: {0, 1, 2, 3}, {0, 1, 2, 4}, {0, 1, 2, 5}, {0, 1, 2, 6}, {0, 1, 2, 7}, {0, 1, 2, 8}, {0, 1, 2, 9}, {0, 1, 3, 4}, {0, 1, 3, 5}, {0, 1, 3, 6}, {0, 1, 3, 7}, {0, 1, 3, 8}, {0, 1, 3, 9}, {0, 1, 4, 5}, {0, 1, 4, 6}, {0, 1, 4, 7}, {0, 1, 4, 8}, {0, 1, 4, 9}, {0, 1, 5, 6}, {0, 1, 5, 7}, {0, 1, 5, 8}, {0, 1, 5, 9}, {0, 1, 6, 7}, {0, 1, 6, 8}, {0, 1, 6, 9}, {0, 1, 7, 8}, {0, 1, 7, 9}, {0, 1, 8, 9}, {0, 2, 3, 4}, {0, 2, 3, 5}, {0, 2, 3, 6}, {0, 2, 3, 7}, {0, 2, 3, 8}, {0, 2, 3, 9}, {0, 2, 4, 5}, {0, 2, 4, 6}, {0, 2, 4, 7}, {0, 2, 4, 8}, {0, 2, 4, 9}, {0, 2, 5, 6}, {0, 2, 5, 7}, {0, 2, 5, 8}, {0, 2, 5, 9}, {0, 2, 6, 7}, {0, 2, 6, 8}, {0, 2, 6, 9}, {0, 2, 7, 8}, {0, 2, 7, 9}, {0, 2, 8, 9}, {0, 3, 4, 5}, {0, 3, 4, 6}, {0, 3, 4, 7}, {0, 3, 4, 8}, {0, 3, 4, 9}, {0, 3, 5, 6}, {0, 3, 5, 7}, {0, 3, 5, 8}, {0, 3, 5, 9}, {0, 3, 6, 7}, {0, 3, 6, 8}, {0, 3, 6, 9}, {0, 3, 7, 8}, {0, 3, 7, 9}, {0, 3, 8, 9}, {0, 4, 5, 6}, {0, 4, 5, 7}, {0, 4, 5, 8}, {0, 4, 5, 9}, {0, 4, 6, 7}, {0, 4, 6, 8}, {0, 4, 6, 9}, {0, 4, 7, 8}, {0, 4, 7, 9}, {0, 4, 8, 9}, {0, 5, 6, 7}, {0, 5, 6, 8}, {0, 5, 6, 9}, {0, 5, 7, 8}, {0, 5, 7, 9}, {0, 5, 8, 9}, {0, 6, 7, 8}, {0, 6, 7, 9}, {0, 6, 8, 9}, {0, 7, 8, 9}, {1, 2, 3, 4}, {1, 2, 3, 5}, {1, 2, 3, 6}, {1, 2, 3, 7}, {1, 2, 3, 8}, {1, 2, 3, 9}, {1, 2, 4, 5}, {1, 2, 4, 6}, {1, 2, 4, 7}, {1, 2, 4, 8}, {1, 2, 4, 9}, {1, 2, 5, 6}, {1, 2, 5, 7}, {1, 2, 5, 8}, {1, 2, 5, 9}, {1,2, 6, 7}, {1, 2, 6, 8}, {1, 2, 6, 9}, {1, 2, 7, 8}, {1, 2, 7, 9}, {1, 2, 8, 9}, {1, 3, 4, 5}, {1, 3, 4, 6}, {1, 3, 4, 7}, {1, 3, 4, 8}, {1, 3, 4, 9}, {1, 3, 5, 6}, {1, 3, 5, 7}, {1, 3, 5, 8}, {1, 3, 5, 9}, {1, 3, 6, 7}, {1, 3, 6, 8}, {1, 3, 6, 9}, {1, 3, 7, 8}, {1, 3, 7, 9}, {1, 3, 8, 9}, {1, 4, 5, 6}, {1, 4, 5, 7}, {1, 4, 5, 8}, {1, 4, 5, 9}, {1, 4, 6, 7}, {1, 4, 6, 8}, {1, 4, 6, 9}, {1, 4, 7, 8}, {1, 4, 7, 9}, {1, 4, 8, 9}, {1, 5, 6, 7}, {1, 5, 6, 8}, {1, 5, 6, 9}, {1, 5, 7, 8}, {1, 5, 7, 9}, {1, 5, 8, 9}, {1, 6, 7, 8}, {1, 6, 7, 9}, {1, 6, 8, 9}, {1, 7, 8, 9}, {2, 3, 4, 5}, {2, 3, 4, 6}, {2, 3, 4, 7}, {2, 3, 4, 8}, {2, 3, 4, 9}, {2, 3, 5, 6}, {2, 3, 5, 7}, {2, 3, 5, 8}, {2, 3, 5, 9}, {2, 3, 6, 7}, {2, 3, 6, 8}, {2, 3, 6, 9}, {2, 3, 7, 8}, {2, 3, 7, 9}, {2, 3, 8, 9}, {2, 4, 5, 6}, {2, 4, 5, 7}, {2, 4, 5, 8}, {2, 4, 5, 9}, {2, 4, 6, 7}, {2, 4, 6, 8}, {2, 4, 6, 9}, {2, 4, 7, 8}, {2, 4, 7, 9}, {2, 4, 8, 9}, {2, 5, 6, 7}, {2, 5, 6, 8}, {2, 5, 6, 9}, {2, 5, 7, 8}, {2, 5, 7, 9}, {2, 5, 8, 9}, {2, 6, 7, 8}, {2, 6, 7, 9}, {2, 6, 8, 9}, {2, 7, 8, 9}, {3, 4, 5, 6}, {3, 4, 5, 7}, {3, 4, 5, 8}, {3, 4, 5, 9}, {3, 4, 6, 7}, {3, 4, 6, 8}, {3, 4, 6, 9}, {3, 4, 7, 8}, {3, 4, 7, 9}, {3, 4, 8, 9}, {3, 5, 6, 7}, {3, 5, 6, 8}, {3, 5, 6, 9}, {3, 5, 7, 8}, {3, 5, 7, 9}, {3, 5, 8, 9}, {3, 6, 7, 8}, {3, 6, 7, 9}, {3, 6, 8, 9}, {3, 7, 8, 9}, {4, 5, 6, 7}, {4, 5, 6, 8}, {4, 5, 6, 9}, {4, 5, 7, 8}, {4, 5, 7, 9}, {4, 5, 8, 9}, {4, 6, 7, 8}, {4, 6, 7, 9}, {4, 6, 8, 9}, {4, 7, 8, 9}, {5, 6, 7, 8}, {5, 6, 7, 9}, {5, 6, 8, 9}, {5, 7, 8, 9}, {6, 7, 8, 9} If repeats are allowed, the number increases to 715 combinations - I'll leave it as an exercise for the reader to list the extra 505 combinations.
8
1. Start with any two numbers . ( Use 0 and 1 to get the standard sequence) 2. 0 1 Rule: Add each pair of numbers to get the next term 0 1 1 ( add 0 + 1 to get 1) 0 1 1 2 ( add 1 + 1 to get 2) 0 1 1 2 3 (1+2 = 3) 0 1 1 2 3 5 (2 + 3 = 5) 0 1 1 2 3 5 8 and so on forever.
1 (0+1) 3 (0+1+2) 6 (0+1+2+3) 10 (0+1+2+3+4) 15 (0+1+2+3+4+5) 21 (0+1+2+3+4+5+6) Notice these are the numbers you can arrange into equalateral triangles.
slope = change_in_y/change_in_x = (2 - 5)/(0 - 1) = -3/-1 = 3