Operation with Functions - h(n)=-3n+5, g(n)=-n^3+1 Find (h-g)(2n)

Question

I got -8n^3-6n+4 as a solution, but none of those choices have that as the answer. What did i do wrong? 

Answer 1

h(n) = -3n + 5

g(n) = -n³ + 1

 

(h - g)(n) = (-3n + 5) - (-n³ + 1)

(h - g)(n) = -3n + 5 + n³ - 1

(h - g)(n) = n³ - 3n + 4

 

(h - g)(2n) = (2n)³ - 3(2n) + 4

 

Try to simplify this one!