这几道题,求帮忙!学霸们帮下!急用!
1.3/(x-4)-24/(x^2-16)
={3(x+4)-24}/(x-4)(x+4)
=(3x-12)/(x-4)(x+4)
=3(x-4)/(x-4)(x+4)
=3/(x+4)
8.(x-4)/(x+2)x(x-2)
9.(2x-5)/(x2-5x+6)=1/(x-2)+1/(x-3)
∴原式=1/(x-2)
10.原式=2(2a-3)/(2a+3)(2a-3) - 3(2a+3)/(2a-3)(2a+3) +15/(2a+3)(2a-3)
=(4a-6-6a-9+15)/(2a+3)(2a-3)
=-2a/(2a+3)(2a-3)
7.解:12/m2-9+2/3-m+2/m+3
=12/(m+3)(m-3)-2(m+3)/(m+3)(m-3)+2(m-3)/(m+3)(m-3)=12-2(m+3)+2(m-3)/(m+3)(m-3)
=0;
4.(1/x-3)+(1-x/6+2x)-(6/x^2-9)
=[2(x+3)+(1-x)(x-3)-6*2]/2*(x^2-9)
=(2x+6-x^2+4x-3-12)/2*(x^2-9)
=(-x^2+6x-9)/2*(x^2-9)
=-(x-3)^2/2*(x+3)(x-3)
=-(x-3)/2*(x+3)
=(3-x)/(2x+6)
被人抢先一步啊