f(x2-2)=lg(x2/x2-5)
2+5x2+5x2=?
15X2/5X2/5X2/5=
x2-5x+1=0则x2+x2/1
2/5x2/4=?
求和Sn=1x2+3x2^2+5x2^3+…+(2n-1)x2^n
(x2+5x+4)2+2(x2+5x+4)2+1=(x2+.
Sn=1x2+3x2^2+5x2^3+...+(2n-1)2^n
解分式方程:2/x2+5x+6 + 3/x2+x-6=4/x2-4
解方程:1/x2+x +1/x2+3x+2 +1/x2+5x+6 +1/x2+7x+12 +1/x2+9x+20=5/x
5x2—[x2+(4x—x2)—2(x2—3x)]
5x2-3x-5=0,求5x2-2x-1/(5x2-2x)=多少?