Practicing Success
If $a^2+c^2+17=2\left(a-8 b-2 b^2\right)$, then what is the value of $\left(a^3+b^3+c^3\right)$ ? |
-7 9 10 -4 |
-7 |
According to the question, a2 + c2 + 17 = 2(a - 8b - 2b2) a2 + c2 + 17 = 2(a - 8b - 2b2) = a2 + c2 + 17 = 2a – 16b – 4b2 = a2 + 4b2 + c2 + 17 = 2(a – 8b) = a2 – 2a + 1 + 4b2 + 16b + 16 + c2 = 0 = (a – 1)2 + (2b + 4)2 + c2 = 0 = a = 1, b = -2 and c = 0 Put the values of a, b and c in (a3 + b3 + c3) (a3 + b3 + c3) = (1)3 + (-2)3 + (0)3 = 1 – 8 + 0 = -7 |