Question

先化简,再求值,x加2分之一减x加2分之x的平方加2x加1除以x减1分之x的平方减1,其

Answer 1

(1-x)/(x+2)+(x²+2x+1)/2÷(x²-1)/x-1

=(1-x)/(x+2)+(x+1)²×(x-1)/(x+1)(x-1)

=(1-x)/(x+2)+(x+1)

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

=(x²+x+3)/(x+2)

x=2时：(2²+2+3)/(2+2)=9/4