Evaluate the function f(x)= 4 • 7^x for x = -1 and x = 2. Show your work.

Now is it asking to be down in two different ways like
f(x)= 4 • 7^-1 and f(x)= 4 • 7^2

If so, did I do them right...
f(x)= 4 • 7^-1
4 • 1/7^1
4/7

f(x)= 4 • 7^2
4 • 49
196

As always any help would be grateful. Thanks.

Question

Evaluate the function f(x)= 4 • 7^x  for x = -1 and x =  2. Show your work.

Now is it asking to be down in two different ways like
f(x)= 4 • 7^-1   and f(x)= 4 • 7^2


If so, did I do them right...
f(x)= 4 • 7^-1 
4 • 1/7^1
4/7

f(x)= 4 • 7^2
4 • 49
196

As always any help would be grateful. Thanks.

danjs · Answer

you have it right

danjs · Answer

what are you asking?

anonymous · Answer

When I first saw the question I thought it was asking to put a number in the (x) spot but I went back to look in my book and never saw it done that way. Just wanted to ask to be safe to know it was done the right way and not to make a fool of myself.

campbell_st · Answer

well another way it to know a little about powers

when multiplying add the powers

$$f(2) = 4\times 7^2 = 4 \times 7^{-1} \times 7^3= \frac{4}{7} \times 7^3$$

which yields the same answer

campbell_st · Answer

you method seems fine, based on the information

anonymous · Answer

Ok,Good. Thanks for the help.