Question

Janice completed the following polynomial addition. Find her error and correct her work.

Answer 1

Answer:

Option B. $9x^{3}-2x^{2}-4x-2$

Step-by-step explanation:

we have

$7x^{3}-2x^{2} +5$

$2x^{3}-4x-7$

Adds the polynomial

Group terms that contain the same variable

$(7x^{3}+2x^{3})-2x^{2}-4x+(5-7)$

Combine like terms

$9x^{3}-2x^{2}-4x-2$

Janice's error was

$-2x^{2} +5-4x-7=6x^{2}-12$

so

$-2x^{2}-4x=6x^{2}$

instead

$-2x^{2}-4x=-2x^{2}-4x$

and

$5-7=-12$

instead

$5-7=-2$