Answer:
see explanation
Step-by-step explanation:
given
(2x + 5)(2x - 1) ← expand using FOIL
(a)
= 4x² - 2x + 10x - 5 ← collect like terms
= 4x² + 8x - 5
(b)
using the method of completing the square on
4x² + 8x - 5 ← factor out 4 from the 1st 2 terms
= 4(x² + 2x) - 5
to complete the square
add/ subtract ( half the coefficient of the x- term )² to x² + 2x
= 4(x² + 2(1)x + 1 - 1) - 5
= 4(x + 1)² - 4 - 5
= 4(x + 1)² - 9
