The equation is 2a-15=-1
It is possible to work out what a is (as I am going to show below), but as there is no y in this equation, you cannot work out what y is.
We have to firstly try and get rid of the -15, so we add 15 to each side, leaving us with 2a=14. To get a on its own, we divide each side by 2, leaving us with a=14.
-16A
-2a - 4 = -16.8 -2a = -12.8 a = -12.8/-2 a = 6.4
a2 + 2a - 15 = 0This can be factorised:a2 + 2a - 15 = (a - 3)(a + 5) = 0So a = 3 and -5.A more robust way is to shove it into the general solution:If αx2 + βx + η = 0, then x = (-β ± √(β2 - 4αγ)) / 2αSo if a2 + 2a - 15 = 0, then:a = (-2 ± √(22 - 4*1*-15)) / 2*1a = (-2±√(64))/2 = (-2±8)/2a = -10/2, 6/2a = -5, 3
2a-5
a = 4
-16A
-2a - 4 = -16.8 -2a = -12.8 a = -12.8/-2 a = 6.4
Do the problem like this: 2a - 15 = -1 Add 15 to both sides: 2a = (-1) + 15 Simplify 2a = 14 Divide by 2 to get the variable by itself: a = 7 Now, check the problem: 2(7) - 15 = -1 14 - 15 = -1 This is true, so a = 7 is a good solution.
a times 2 equals 2a
a2 + 2a - 15 = 0This can be factorised:a2 + 2a - 15 = (a - 3)(a + 5) = 0So a = 3 and -5.A more robust way is to shove it into the general solution:If αx2 + βx + η = 0, then x = (-β ± √(β2 - 4αγ)) / 2αSo if a2 + 2a - 15 = 0, then:a = (-2 ± √(22 - 4*1*-15)) / 2*1a = (-2±√(64))/2 = (-2±8)/2a = -10/2, 6/2a = -5, 3
2a-5
a = 4
2a - a = a
sqrt(4a2) = 21plus or minus (2a) = 21plus or minus (a) = 10.5a = +10.5a = -10.5
2a+5
To solve this, isolate x. first, add 10 to both sides. this will leave you with 2a + 15 = a Then, subtract 2a from both sides. This will leave you with 15 = -a Therefore, -15 = a
x equals negative b plus or minus the square root of b squared minus 4bc over 2a