Question

Simplify (4x^2 - 8xy + 2y^2) - (9x^2 - 4xy - 7y^2)

a. -5x^2 + 4xy + 9y^2
b. -5x^2 - 4xy + 9y^2
c. -5x^2 + 12xy + 4y^2
d. -5x^2 - 4xy - 5y^2

Answer 1

b

Explanation:

Distribute parenthesis and collect like terms, noting that the second parenthesis is distributed by - 1

(4x² - 8xy +2y²) - (9x² - 4xy - 7y²)

= 4x² - 8xy + 2y² - 9x² + 4xy + 7y² ← collect like terms

= (4x² - 9x²) + (- 8xy + 4xy) + (2y² + 7y²)

= - 5x² - 4xy + 9y² → b

Answer 2

Choice b is correct answer.

Explanation:

Given expression is:

(4x²-8xy+2y²) - ( 9x²-4xy-7y²)

We have to simplify above expression.

Step 1 . Open small brackets and multiply negative sign to the terms of second small bracket.

4x² - 8xy + 2y² - 9x² + 4xy + 7y²

Step 2. Gather like terms

4x²-9x²-8xy+4xy+2y²+7y²

Step 3. Add the coefficients of like terms

(4-9)x²+(-8+4)xy+(2+7)y²

(-5)x²+(-4)xy+(9)y²

-5x²-4xy+9y² which is the final answer.