3x(3x2-4x+9)+(4x+5)(-4x-5)1

(x+3/x2-9+x/6+x-x2)(3-x/4x-6) (x2+4x-5)(x2+4x+3)最小值 计算:x2-5x+6/x2-4x+3 + x2-4x+3/x2-2x+1 + x2-3x-4/1-x2 5x2—[x2+(4x—x2)—2(x2—3x)] (-2x)*(x2-5x+6)-4x(2x2-3x+1) (-x 2x2-3 x 1) 2(x 2x -5)-(4x2-3x 5 x 1)的计算 x2-4x+3分之x2-5x+6+s2-2x+1分之x2-4x+3+1-x2分之x2-3x-4的过程 1/(x2+x)+1/(x2+3x+2)+1/(x2+5x+6)+1/(x2+7x+12)=4/21x2是x的平方 3x(3x2-4x+9)+(4x+5)(-4x-5)1 通分 3x/x2-2x,2x+1/4-x2,3/2x2+4x 3/x2 -3x+2-1/x-2=1/x2 -x+4/x2 -2x 5(x2-x)=3(x2+x) (x+1)(x2-x+1)+(x-2)(x2+2x+4),其中x=-3/2 1.18-2（3-4X)=10X2.X/2-X=(X+5)-2X 1.2-5x+x*x2.2x*x-5x+13.x*x-3/2*x-24.-x*x-4x+3 约分 1-x2/x2-3x-4 (x+3)(x+5)+x2-9 A={x|x2-4x+3