先化简,在求值 1/x+1-x+3/x²-1*x²-2x+1/x²+4x+3,其中x=2

题目

先化简,在求值 1/x+1-x+3/x²-1*x²-2x+1/x²+4x+3,其中x=2

答案

原式=1/(x+1)-(x+3)/(x+1)(x-1)*(x-1)²/(x+3)(x+1)
=1/(x+1)-(x-1)/(x+1)²
=(x+1-x+1)/(x+1)²
=2/(x+1)²
=2/9