Question

Let f(x)=7x^2-8. find f(a^2)

Answer 1

`\large\boxed{f(a^2)=7a^4-8}`

Explanation:

`f(x)=7x^2-8\\\\f(a^2)\to \text{put}\ x=a^2\ \text{to the equation of the function}\ f:\\\\f(a^2)=7(a^2)^2-8\qquad\text{use}\ (a^n)^m=a^(nm)\\\\f(a^2)=7a^(2\cdot2)-8\\\\f(a^2)=7a^4-8`