Question

Let f(x) = 6x-5 and g(x) = 2x-1. Find f • g

I thought the answer was 12x^3 - 6x^2 - 10x + 5 but my computer says it's wrong

Answer 1

f of g = 6(2x-1) - 5

12x - 6 - 5

12x - 11

Instead of just multiplying the binomials, f of g implies actually substituting the value of g for every appearance of x in the value of f. If it asked for g of f, you would substitute the x in 2x - 1 with 6x - 5, so it would be 2(6x-5) - 1.