Answer:
A: This quadratic expression can be factored by finding the correct pair of binomial factors
B: 4x + 5
B: 2x - 3
Explanation:
8x² - 2x - 15 can only be factorised by finding a correct pair of binomial factors because 15 and 8 are not a perfect square.
Thus,
To find the correct pair, find the 2 numbers that would give us -120 (8*15) when multiplied, and would also give us -2 when added together.
(-12) × (+10) = -120
(-12) + (+10) = -2
-12 and +10 would be the factors to use. Thus, let's factorised as follows:
8x² - 2x - 15
8x² - 12x + 10x - 15
(8x² - 12x) + (10x - 15)
Look for common factors
4x(2x - 3) +5(2x - 3)
(4x + 5)(2x - 3)