diketahui f(x)=x^+2x dan g(x)=3x-1 tentukan fg(x), fog(x), gof(-1), dan f+g(x)

jawab

f(x) = x² + 2x
g(x)= 3x - 1

fog(x) =f{g(x)} = f(3x -1)
= (3x-1)² + 2(3x-1)
= 9x² -6x + 1 + 6x - 2
= 9x² - 1

gof(-1) = g {f(-1)} = g {(-1)² +2(-1)} = g(1-2) = g(-1)
= 3(-1)  - 1
= - 3 - 1
= - 4

(f + g)(x)= f(x) + g(x) = x² + 2x + 3x - 1
= x² + 5x - 1