先化简再求值X-2/X^2-1+2X+2/X^2+2X+1-1/X-1,其中X=√2+1
1个回答

你的题目是(X-2)/(X^2-1)+(2X+2)/(X^2+2X+1)-1/(X-1)吗?

如果是则

(X-2)/(X^2-1)+(2X+2)/(X^2+2X+1)-1/(X-1)

=(X-2)/(X^2-1)+2(X+1)/(X+1)^2-1/(X-1)

=(X-2)/(X^2-1)+2/(X+1)-1/(X-1)

=[(x-2)+2(x-1)-(x+1)]/(X^2-1)

=(2x-5)/(X^2-1)

=(2√2+2-5)/(2+1+2√2-1)

=(2√2-3)/(2√2+2)

=(2√2-3)(2√2-2)/[(2√2-2)(2√2+2)]

=(8-10√2+6)/4

=(7-5√2)/2