Question

If f(x) = 4 – x2 and g(x) = 6x, which expression is equivalent to (g – f)(3)?

Answer 1

`(g-f)(3)=23`

Explanation:

`(g-f)(x)=g(x)-f(x)`

`color(white)(xxxxxx)=6x-(4-x^2)`

`color(white)(xxxxxx)=x^2+6x-4`

`"to evaluate "(g-f)(3)" substitute x = 3 into "(g-f)(x)`

`(g-f)=(color(red)(3))^2+(6xxcolor(red)(3))-4=23`

Answer 2

23

Explanation:

`g-f = 6x -(4-x²) = x² + 6x - 4`
`(g-f)(3) = 3² + 6*3 - 4 = 9 + 18 - 4 = 23`