明天考，急问JJ一道！MATH

19、 已知，a=x+1/x,b=x-1/x，求2^（a^2）/2(b^2) 实际上知道a^2-b^2=4就行了，
                

答案16

a^2-b^2明明等于X分之4吗？

a^2-b^2明明等于X分之4吗？

Please read JJ 19

goes like (x+1/x)(x+1x) - (x-1/x)(x-1/x) then do the whole muti .. you'll get 4  and 2^4 = 16.... that's the NONE NN way of doing it... so you can get the answer, just take a little time..