Question

七年级分式数学题

2x-4分之7 — x+2分之3 + 4-x²分之12
详细过程！！！

Answer 1

7/(2x-4)-3/(x+2)+12/(4-x²)
=7/[2(x-2)]-3/(x+2)+12/[(2+x)(2-x)]
=7/[2(x-2)]-3/(x+2)-12/[(x+2)(x-2)],最小公分母是：2(x+2)（x-2)
=7(x+2)/[2(x+2)(x-2)]-3×2(x-2)/[2(x+2)(x-2)]-12×2/[2(x+2)(x-2)]
=[7(x+2)-6(x-2)-24]/[2(x+2)(x-2)]
=(7x+14-6x+12-24)/[2(x+2)(x-2)]
=(x+2)/[2(x+2)(x-2)]
=1/(2x-4)

Answer 2

解：原式=7/(2x-4)-3/(x+2)+12/(4-x²)
=7/[2(x-2)]-3/(x+2)+12/[(2+x)(2-x)]
=7/[2(x-2)]-3/(x+2)-12/[(x+2)(x-2)]
=7(x+2)/[2(x+2)(x-2)]-3×2(x-2)/[2(x+2)(x-2)]-12×2/[2(x+2)(x-2)]
=[7(x+2)-6(x-2)-24]/[2(x+2)(x-2)]
=(7x+14-6x+12-24)/[2(x+2)(x-2)]
=(x+2)/[2(x+2)(x-2)]
=1/(2x-4)

Answer 3

解：7/2(x-2)-3/(x+2)+12/(4-x^2)=7/2(x-2)-3/(x+2)-12/(x-2)(x+2)=[7(x+2)-6(x-2)-24]/2(x-2)(x+2)
=(x+2)/2(x-2)(x+2)=1/(2x-4)

Answer 4

通分，公分母为2（x^2-4）,分子相加减为：7(x+2)-3*2(x-2)-12*2=x+2,x+2与分母2（x^2-4）约分，得最后结果为2x-4分之1