Question

Find the values for A and B that would make the equality true

-5(3x^2+5x+b)=ax^2-25x+45

Answer 1

a = - 15 and b = - 9

Explanation:

distribute the left side

- 15x² - 25x - 5b

For - 15x² - 25x - 5b = ax² - 25x + 45

Then the coefficients of like terms must be equal, hence

comparing coefficients of x² term ⇒ a = - 15

comparing constant term ⇒ - 5b = 45 ⇒ b = - 9

Answer 2

Answer: a = -15, b = -9

Explanation:

-5(3x² + 5x + b) = ax² - 25x + 45

-15x² - 25x - 5b = ax² - 25x + 45 distributed -5 on left side

Notice that the middle terms (-25x) are equal, so the the remaining terms will also be equal.

-15x² = ax² ⇒ -15 = a

-5b = 45 ⇒ b = -9