Add or subtract as indicated.
-$\left(-2 r^{4}+9 r^{3}-3 r\right)-\left(8 r^{4}-9 r^{3}+6 r^{2}-2 r\right)$
A) $-6 r^{4}-6 r^{2}+r$
B) $10 \mathrm{r}^{4}-18 \mathrm{r}^{3}+6 \mathrm{r}^{2}+\mathrm{r}$
C) $6 r^{4}+6 r^{2}-r$
D) $-10 r^{4}+18 r^{3}-6 r^{2}-r$

Question

Quizplus · Accepted Answer

Subtracting the second polynomial from the first involves changing the signs of the second polynomial and then adding. The correct subtraction gives $(-2r^4 + 9r^3 - 3r) - (8r^4 - 9r^3 + 6r^2 - 2r) = -2r^4 + 9r^3 - 3r - 8r^4 + 9r^3 - 6r^2 + 2r = -10r^4 + 18r^3 - 6r^2 - r$.

Add or Subtract as Indicated (−2r4+9r3−3r)−(8r4−9r3+6r2−2r)\left(-2 r^{4}+9 r^{3}-3 r\right)-\left(8 r^{4}-9 r^{3}+6 r^{2}-2 r\right)(−2r4+9r3−3r)−(8r4−9r3+6r2−2r)

Add or Subtract as Indicated $\left(-2 r^{4}+9 r^{3}-3 r\right)-\left(8 r^{4}-9 r^{3}+6 r^{2}-2 r\right)$