Given that 2^x = 7, find the value of (4^x-1)
Note: It is find the value of 4 to the power of x-1.
4^x is 2^2x which is (2^x)(2^x)
this is 7*7 which gives 49
since exponent is subtracting one, we divide by four
and get 49/4
+130 
