What is the effect on the graph of the function f(x) = 2x when f(x) is replaced with f(−5x)?

What is the value of x when x + 7 = 21?

Describe the end behavior of the function below. f(x)=(2/3)^x-2 a. as x increases, f(x) approaches infinity. b. as x decreases, f(x) approaches 2. c. as x increases, f(x) approaches -2. d. as x decreases, f(x) approaches negative infinity.

Ithink i know it but i want to be sure so can you me out ?