1楼 (6x+7)²(3x+4)(x-1)=6 求x的值 (6x+7)右上角那个是平方
1个回答

(6x+7)^2(3x+4)(x+1)=6

(36x^2+84x+49)(3x^2+7x+4)=6,

令3x^2+7x+4=t,则36x^2+84x+49=12t+1,

原方程成为(12t+1)t=6,

12t^2+t-6=0,

(4t+3)(3t-2)=0,

(1).t=-3/4时,3x^2+7x+4=-3/4,

12x^2+28x+19=0,无实根.

(2).t=2/3时,3x^2+7x+4=2/3,

9x^2+21x+10=0,

(3x+2)(3x+5)=0,

x1=-2/3,x2=-5/3.