B. 3x² − 10x − y
Step-by-step explanation:
To simplify this, we combine like terms:
2x - 8y + 3x² + 7y - 12x
2x has a like term with -12x; 2x-12x = -10x. This gives us
-10x - 8y + 3x² + 7y
-8y has a like term with 7y; -8y+7y = -1y. This gives us
-10x - 1y + 3x²
In order by power of x, we have
3x² - 10x - y