Question

先化简,再求值(3a/a-1 -a/a+1)(a2-1/a),其中a=根号2-2？

Answer 1

原式=3a/(a-1)*(a+1)(a-1)/a-a(a+1)*(a+1)(a-1)/a
=3(a+1)-(a-1)
=3a+3-a+1
=2a+4
当a=√2-2 时,原式=2*（√2-2）+4
=2√2
答：所求式的化简结果为2a+4
当a=-2 时,求值结果为2√2 .,6,
sljwendy 举报
原式=3a/(a-1)*(a+1)(a-1)/a-a/(a+1)*(a+1)(a-1)/a 是这样吗？ 谢谢 是的 不客气,=[(3a²+3a-a²+a)/(a²-1)×(a²-1)/a
=2a+4
=2(√2-2)+4
=2√2,0,原式=[3a/(a-1)-a(a+1)](a+1)(a-1)/a
=3a/(a-1)*(a+1)(a-1)/a-a(a+1)*(a+1)(a-1)/a
=3(a+1)-(a-1)
=3a+3-a+1
=2(a+2)
=2(√2-2+2)
=2√2,0,