Which graph represents the function f(x)=−2x−1 ?

Question

the x is an exponent

Answer 1

You need to know what the graph of g(x) = 2^x looks like.  It's probably in your text book, or you can look it up on the internet.  Changing the 2 to -2 flips (reflects) the graph across the x-axis.  The -1 moves the whole graph down 1 along the y-axis.