Question

f(x)=5x+4
g(x)=7x^2+3
find -3•(g-f)(0)

Answer 1

$f(x)=5x+4\\\\g(x)=7x^2+3\\\\(g-f)(x)=g(x)-f(x)=(7x^2+3)-(5x+4)\\\\=7x^2+3-5x-4=7x^2-5x-1\\\\-3(g-f)(x)=-3(7x^2-5x-1)=-21x^2+15x+3$