解方程3条
问题描述：
解方程3条
x^2-2x-1=0
2y^2+y-1=0
2logx 25-3log25 x=1
答
x^2-2x-1=0x^2-2x=1x^2-2x+1=1+1(x-1)^2=2x-1=√2或x-1=-√2x1=√2+1 x2=-√2+12y^2+y-1=0(y+1)(2y-1)=0y1=-1 y2=1/22lg25/lgx -3lgx/lg25=1令t=lgx,则2lg25/t-3t/lg25=1两边乘以t*lg25,2lg25*lg25-3t^2-t*lg25=03t^...