If r(x)=4x-3x+7, find r(3a)

Question

The 3a is squared and the 4x is squared

Answer 1

If i understand correctly, you are solving:

r(3a²) when r(x) = 4x² - 3x + 7

Replace all values of x in r(x) with 3a²

4(3a²)² - 3(3a²) + 7

4(9a4) - 9a² + 7

36a⁴ - 9a² + 7