一道初二分式化简题
问题描述:
一道初二分式化简题
7/(2x+6x)-(11-2x²)/(9-x²)+2化简
我看答案是7/(6x-2x²)
我要过程
答
写错了,应该是
7/(2x²+6x)-(11-2x²)/(9-x²)+2
=7/[2x(x+3)]-(2x²-11)/(x²-9)+2
=7/[2x(x+3)]-(2x²-11)/(x+3)(x-3)+2
=[7(x-3)-2x(2x²-11)+2*2x(x+3)(x-3)]/[2x(x+3)(x-3)]
=(7x-21-4x³+22x+4x³-36x)/[2x(x+3)(x-3)]
=(-7x-21)/[2x(x+3)(x-3)]
=-7(x+3)/[2x(x+3)(x-3)]
=7/(6x-2x²)