4^x - 2^x = 2
(2^x)² - 2^x - 2 = 0
(2^x + 1)(2^x - 2) = 0
2^x = 2
x = 1(2^x + 1)(2^x - 2) = 0这部怎么来的啊?可以这样的啊?化出来都不等于上一步- -(2^x + 1)(2^x - 2) =2^x *2^x-2*2^x+2^x-2 =(2^x)²-2^x - 2 楼主，等于上一步的2^x = 2这步呢- -不是等于4^x=2咩不是，4^x=2^2x=(2^x)^2=4