Question

P=-4a^2-2ab+9b^2
Q=-7a^2-3ab+5b^2
P-Q

Answer 1

3a² + ab + 4b²

Explanation:

P - Q

= - 4a² - 2ab + 9b² - (- 7a² - 3ab + 5b² ) ← distribute parenthesis by - 1

= - 4a² - 2ab + 9b² + 7a² + 3ab - 5b² ← collect like terms

= 3a² + ab + 4b²

Answer 2

3a² + ab + 4b²

Explanation:

Combine like terms. Like terms have same variable with same power.

P - Q = -4a² - 2ab + 9b² - (-7a² - 3ab + 5b²)

To open the brackets, multiply each term of Q by (-1)

= -4a² - 2ab + 9b² + 7a²+ 3ab - 5b²

-4a² and 7a² are like terms.

(-2ab) and 3ab are like terms.

9b² and (-5b²) are like terms.

= -4a² + 7a² -2ab + 3ab + 9b²- 5b²

= 3a² + ab + 4b²