Question

通分 1.a/(a^2-9),a-1/a^2+6a+9 2.x/2(x+1),1/x^2-x 3.1/x^2-4,x/4

Answer 1

通分

1、a/(a^2-9)和(a-1)/a^2+6a+9,

a/(a^2-9)=a/(a+3)(a-3),

(a-1)(/a^2+6a+9) =(a-1)/(a+3)^2(a+3)=(a-1)/(a+3)(a+3),

公分母 (a+3)(a+3)(a-3),

即a/(a^2-9)=a/(a+3)(a-3)= a(a+3)/(a+3)(a+3)(a-3),

(a-1)(/a^2+6a+9) =(a-1)/(a+3)^2(a+3)=(a-1)/(a+3)(a+3)=(a-1)(a-3)/a+3)(a+3)(a-3).

2、x/2(x+1)和1/(x^2-x),

1/(x^2-x)=1/x(x-1),公分母为2x(x-1)(x+1),即

x/2(x+1) = x^2 * (x-1)/2x(x-1)(x+1),x^2为x的平方,

11/(x^2-x)=1/x(x-1)= 2(x+1)/2x(x-1)(x+1).

3、1/(x^2-4)和x/(4-2x),

1/(x^2-4) = 1/(x+2)(x-2),

x/(4-2x) = x/2(2-x),

公分母为2(x+2)(x-2),则

1/(x^2-4) = 1/(x+2)(x-2) = 2/2(x+2)(x-2),

x/(4-2x) = x/2(2-x) = - x(x+2)/2(x+2)(x-2)