If h(x)= 2x and g(x)= 3x^2+1, what is h(g(x))?

Answer 1

x is just a place holder. It can be replaced with anything, such as
h(6) = 2*6
h(cows) = 2cows
so,
h(g(x)) = 2g(x) = 2(3x^2+1) = 6x^2+2