Question

数学化简求值

①.(x+1分之1 + x-1分之1)× x的二次方-1,其中x=2分之1
②x的二次方-2x+1分之x的二次方-x - x+1分之x，其中x=根号2

拜托~~~~~~~

Answer 1

解：（1）原式=（x²-1)/(x+1)+(x²-1)/(x-1)=x-1+x+1=2x=2×1/2=1
(2)原式=x(x-1)/(x-1)²-x/(x+1)
=x/(x-1)-x/(x+1)
=(x²+x)/(x²-1)-(x²-x)/(x²-1)
=2x/(x²-1)
=2√2/(2-1)
=2√2

追问

下次最好还是写一下当x=...时，原式=.....，比较好认，谢了~