用对数恒等式.2^log(4)(3)+3^log(9)(1/4)+5^log(1/25)(2)=【4^log(4)(3)】^（1/2）+【9^log(9)(1/4)】^（1/2）+【25^log(25)(1/2)】^（1/2）=3^（1/2）+(1/4)^（1/2）+（1/2）^（1/2）=√3+1/2+√2/2....