3^x - 3^x-1 =162, then x(x-1)=
a 12
b 16
c 20
d 30
e 81
i know this is easy but i couldn't get it
a 12
b 16
c 20
d 30
e 81
i know this is easy but i couldn't get it
Try this:
3^x-1 = (3^x)/3
3^x - 3^x-1 = 3^x - (3^x)/3 = (2 * 3^x)/3 = 162
=> x = ...
