20[1/X+1/(X+30)]=1 怎么解,
问题描述:
20[1/X+1/(X+30)]=1 怎么解,
答
两边同时乘以x(x+30)有
20*[(x+30)+ x ] = x*(x+30)
x*x - 10*x - 20*30 = 0
(x-30)*(x+20) = 0
x=30 或-20