Answer:
f(g)(k) = 150k² + 160k + 42
Explanation:
f(g(k) )
g(x) = 5x + 3 , then g(k) = 5k + 3
= f(5k + 3) ← substitute x = 5k + 3 into f(x)
= 6(5k + 3)² - 4(5k + 3) ← expand (5k + 3)² using FOIL
= 6(25k² + 30k + 9) - 4(5k + 3) ← distribute parenthesis
= 150k² + 180k + 54 - 20k - 12 ← collect like terms
= 150k² + 160k + 42