Evaluate the function f(x)=4•7^x for x=-1 and x2 show your work

When you evaluate the function f (x) = 4 • 7 ^ x for x = -1 you get:
 f (-1) = 4 * 7 ^ -1
 f(-1) = 4* 1/7
 f (-1) = 0.5714
 The next part of the question is not clear. If it refers to the function at x = 2 then:
 f (2) = 4 * 7 ^ (2)
 f(2) =4*49
 f (2) = 196
 If it refers to it in x ^ 2
 f (x ^ 2) = 4 * 7 ^ (x ^ 2)

That’d be 9 years or something