Question

If s(x) = 2 - x and f(x) = 3x, which value is equivalent to (s f) (-7)

Answer 1

Explanation:

the first method :

s(x) = 2 - x and f(x) = 3x

(s f) (-7) = s(-7) ×f(-7)

but : s(-7) = 2 - (-7) =2+7 = 9

f(-7) = 3(-7) = - 21

so : (s f) (-7) = (9)×(-21) = - 189

the second method :

calculate : (s f) (x) == s(x)×f(x) = (2-x) 3x = 6x - 3x²

(s f) (-7) = 6(-7) -3 (-7)² = - 42 -147 = -189