7 6 4 6 2 6 1 6
7-1=3 6/2=3
1 (1) 3 (1 + 2) 6 (1 + 2 + 3) 10 (1 + 2 + 3 + 4) 15 (1 + 2 + 3 + 4 + 5) 21 (1 + 2 + 3 + 4 + 5 + 6) 28 (1 + 2 + 3 + 4 + 5 + 6 + 7) 36 (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8) 45 (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9) 55 (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) 66 (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11) 78 (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12)
6?! 1-2 2-3 3-4 4-5 5-6 6-7
Guessing that is: 9 2/7 - 6 5/7 = (8 + 1 + 2/7) - 6 5/7 = (8 + 7/7 + 2/7) - 6 5/7 = 8 9/7 - 6 5/7 = 2 4/7 Alternatively, using improper fractions: 9 2/7 - 6 5/7 = (9x7+2)/7 - (6x7+5)/7 = 65/7 - 47/7 = 18/7 = (2x7+4)/7 = 2 4/7
To solve:-3x + 2y = 7y = x2 - 2x + 3re-arrange the first to make y the subject and substitute for y in the second:y = 1/2 (7 + 3x)1/2 (7 + 3x) = x2 - 2x + 3And solving the second:1/2 (7 + 3x) = x2 - 2x + 3→ 7 + 3x = 2x2 - 4x + 6→ 2x2 - 7x - 1 = 0→ x = 1/4 (7 ± √57)And substituting back into the (rearranged) first equation:y = 1/2 (7 + 3x)= 1/2 (7 + 3(1/4 (7 ± √57)))= 1/2 (28/4 + 3/4 (7 ± √57)))= 1/8 (49 ± 3√57)giving the two solutions:x = 1/4 (7 + √57) ≈ 3.637, y = 1/8 (49 + 3√57) ≈ 8.956x = 1/4 (7 - √57) ≈ -0.137, y = 1/8 (49 - 3√57) ≈ 3.294Note: the value of y is worked out once for each of the +/- of the √57; in this case +√57 for x leads to +√57 for y, and -√57 for x leads to -√57 for y. I showed the calculation in one for both.To check the result, a substitution can be made in the original equation 2:x = 1/4 (7 ± √57):y = (1/4 (7 ± √57))2 - 2(1/4 (7 ± √57)) + 3= 1/16 (7 ± √57))2 - 8/16(7 ± √57) + 48/16= 1/16 (49 ± 14√57 + 57 - 56 - ±8√57 + 48)= 1/16 (96 ± 6√57) [see below]= 1/8 (49 ± 3√57) as beforeIn simplifying ±14√57 - ±8√57 = (±14 - ±8)√57 the + and - signs of the 14 and 8 correspond to give:"+14" goes with "- +8" to give 14 - (+8) = 14 - 8 = +6"-14" goes with "- -8" to give -14 - (-8) = -14 + 8 = -6
The factors of 57 are 1, 3, 19, and 57The factors of 18 are 1, 2, 3, 6, 9, and 18
The factors of 57 are:1, 3, 19, 57The factors of 84 are:1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, 84The common factors are:1, 3
1, 3, 19 and 57
8.1429
The answer is 6 / (1-5/7). 1- 5/7 = 2/7 6 / (2/7) = 6 * (7/2) = (6*7)/2 = 42/2 = 21. Simples!
You havey = 4x + 8x² + 7x - 2 = 0The second is a quadratic involving only x so solve {2} first to find the x values, which can be substituted into the first to find the corresponding y value. x² + 7x - 2 = 0→ x = (-7 ± √(7² - 4×1×-2))/(2×1) = (-7 ± √57)/2→ x = (-7 - √57)/2→ y = 4 × (-7 - √57)/2 + 8 = -6 - 2√57or x = (-7 + √57)/2→ y = 4 × (-7 + √57)/2 + 8 = -6 + 2√57The solution is the two ordered pairs (x, y)::( (-7 - √57)/2, -6 - 2√57) and ((-7 + √57)/2, -6 + 2√57)
19/6 = 57/18 16/9 = 32/18 57 - 32 = 25 25/18 = 1 and 7/18
4/7 * 1/6 = (4*1)/(7*6) = (2*1)/(7*3) = 2/21
(7 + 1) × 6 ÷ 2 = 24.
6 x (7 - 2) + 1 = 31
7 6 4 6 2 6 1 6