Subtract.
-$\left(-9 x^{7}+8 x^{9}-8-3 x^{8}\right)-\left(-4-9 x^{8}+4 x^{9}-3 x^{7}\right)$
A) $4 x^{9}-12 x^{8}-12 x^{7}-12$
B) $4 x^{9}+6 x^{8}-6 x^{7}-4$
C) $12 x^{9}-12 x^{8}-12 x^{7}-12$
D) $12 x^{9}-12 x^{8}-12 x^{7}-4$

Question

Quizplus · Accepted Answer

Subtracting the second polynomial from the first involves changing the signs of the second polynomial and then combining like terms. The correct subtraction is $(-9x^7 + 8x^9 - 8 - 3x^8) - (-4 - 9x^8 + 4x^9 - 3x^7) = -9x^7 + 8x^9 - 8 - 3x^8 + 4 + 9x^8 - 4x^9 + 3x^7 = 4x^9 + 6x^8 - 6x^7 - 4$.

Subtract - (−9x7+8x9−8−3x8)−(−4−9x8+4x9−3x7)\left(-9 x^{7}+8 x^{9}-8-3 x^{8}\right)-\left(-4-9 x^{8}+4 x^{9}-3 x^{7}\right)(−9x7+8x9−8−3x8)−(−4−9x8+4x9−3x7) A) 4x9−12x8−12x7−124 x^{9}-12 x^{8}-12 x^{7}-124x9−12x8−12x7−12

Subtract
- $\left(-9 x^{7}+8 x^{9}-8-3 x^{8}\right)-\left(-4-9 x^{8}+4 x^{9}-3 x^{7}\right)$ A) $4 x^{9}-12 x^{8}-12 x^{7}-12$