1/(x+1)-1/(x+2)=1/(x+9)-1/(x+10)
1/(x+1)(x+2)=1/(x+9)(x+10)
所以(x+1)(x+2)=(x+9)(x+10)
x²+3x+2=x²+19x+90
16x=-88
x=-11/2
1/(x+1)-1/(x+2)=1/(x+9)-1/(x+10)
[(x+2)-(x+1)]/[(x+1)(x+2)]=[(x+10)-(x+9)]/[(x+9)(x+10)]
1/[(x+1)(x+2)]=1/[(x+10)(x+9)]
(x+10)(x+9)=(x+1)(x+2)
解得
x=11/2
检验:
1/(x+1)+1/(x+10)=1/(x+2)+1/(x+9)
(2x+11)/(x^2+11x+10)=(2x+11)/(x^2+11x+18)
8(2x+11)=0
x=5.5
无解
1/(x+1)+1/(x+10)=1/(x+2)+1/(x+9)
1(x+1)-1/(x+2)=1/(x+9)-1/(x+10)
(x+1)(x+2)=(x+9)(x+10)
x=-11/2