Question

Lucia finds that (3x²+3x+5)+(7x²-9x+8)=10x²-12x+13. What error did Lucia make?

A)She found the difference instead of the sum.
B)She combined the terms 3x² and 7x² incorrectly.
C)She combined the terms 3x and –9x incorrectly.
D)She did not combine all like terms.

Answer 1

lucia combined like terms in correctly
your answer is c,
she should have gotten -6x
because -9+3=6

her answer should be 10^2 -6x+13

Answer 2

The answer is the option C

She combined the terms
`3x` and
`-9x` incorrectly

Explanation:

we have

`(3x^(2) +3x+5)+(7x^(2)-9x+8)`

Group terms that contain the same variable

`(3x^(2)+7x^(2))+(3x-9x)+(5+8)`

Combine like terms

`(10x^(2))+(-6x)+(13)`

Lucia combined the terms
`3x` and
`-9x` incorrectly