If k(x)=3x2-6x,find k(6)and k(-7).

Question

If k(x)=3x^2−6x, find k(6)and k(−7).

Answer 1

simple substitution and evaluation

 

k(x) = 3x²−6x

k(6) = 3(6²) - 6(6)

k(6) = 3(36) - 36

k(6) = 108 - 36

k(6) = 72

 

k(x)  = 3x²−6x
k(-7) = 3(-7²) - 6(-7)
k(-7) = 3(49) - -42
k(-7) = 147 + 42
k(-7) = 189