1/X(X+1)+1/(X+1)(X+2)+1/(X+2)(X+3)其中X的平方+3X+1=0

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1/X(X+1)+1/(X+1)(X+2)+1/(X+2)(X+3)其中X的平方+3X+1=0

1/X(X+1)+1/(X+1)(X+2)+1/(X+2)(X+3)其中X的平方+3X+1=0
1/X(X+1)+1/(X+1)(X+2)+1/(X+2)(X+3)其中X的平方+3X+1=0

1/X(X+1)+1/(X+1)(X+2)+1/(X+2)(X+3)其中X的平方+3X+1=0
第一题
由X^2+3X+1=0,得X^2=-3X-1代入,
1/(X+1)(X+2)=1,故原式=1/X(X+1)+1+1/(X+2)(X+3)=
1+1/(-1-2X)+1/(2X+5)通分,原式=1+4/-(2X+5)(2X+1)=
1+4/-[4(X^2+3X+1)+1]=1-4=-3
第二题
移项,1/(x-10)-1/(x-7)=1/(x-9)-1/(x-6),通分得
3/(x^2-17x+70)=3/(x^2-15x+54),即(x^2-17x+70)=(x^2-15x+54),
得x=8