Question

If f(x)=x² – 4x, what is the value of 2f(a-1)?

Answer 1

2a² - 12a + 10

Explanation:

f(x) = x² – 4x

2f(a-1) = 2[(a-1)² - 4(a-1)]

= 2[a² -2(a)(1) + 1² - 4a + 4]

=2[a² - 2a + 1 -4a + 4]

= 2(a² -6a + 5)

= 2a² - 12a + 10