Question

数学-化简求值(1)先化简再求值:1+X/1-X÷(X-2X/1-X),其中X=2.(2)化简求值:(a^2+b^2/a

Answer 1

1）

1+X/1-X÷(X-2X/1-X),

=(1+x)/(1-x)÷(-x-x^2)/(1-x)

=(1+x)/(1-x)×(1-x)/[-x(x+1)]

=-1/x

=-1/2

2)

(a^2+b^2/ab+2)÷a^2-b^2/a-b

=(a^2+b^2+2ab)/ab÷(a-b)(a+b)/(a-b)

=(a+b)^2/ab×1/(a+b)

=(a+b)/ab

=1/b+1/a

=2+1/2

=5/2