用配方法解下列方程(1)X^2-6X+4=0（2）X^2+5X-6=0 （3）2t^2-7t-4=0(4)3X^2-1=6X

显示全部楼层 · 2011-9-7 20:29:24

(1)X^2-6X+4=0X2-6X+9-5=0(X-3)2=5X-3=±√5X1=3+√5X2=3-√5(2)X^2+5X-6=0 X2+5X=6 X2+5X+(5/2)2=6+25/4(X+5/2)2=49/4X+5/2=±7/2X1=-5/2+7/2=1X2=-5/2-7/2=-6(3)2t^2-7t-4=0t2-7t/2-2=0t2-7t/2+(7/4)2=2+49/16(t-7/4)2=81/16t-7/4=±9/4t1=7/4+9/4=4t2=7/4-9/4=-1/2...

千问 · 2011-9-7 20:29:24

X^2-6X+4=0 (x-3)^2=5,x=3±√5X^2+5X-6=0 (x+5/2)^2=6+25/4=49/4,x=-5/2±7/2，x=1或-6 2t^2-7t-4=0 t^2-7/2t-2=0(t-7/4)^2=2+49/16=81/16,t=7/4±9/4，t=4或-1/23X^2-1=6X x^2-2x-1/3...

千问 · 2011-9-7 20:29:24

0=X^2-6X+3X^2-60=(x-3)^2-6(x-3)^2=6x-3=根号6x=根号6=3...

千问 · 2011-9-7 20:29:24

0.6，0.89/5，2/3...

千问 · 2011-9-7 20:29:24

(1)X^2-6X+4=0(x-3)^2=5,x=3±√5（2）X^2+5X-6=0(x+5/2)^2=6+25/4=49/4,x=-5/2±7/2，x=1或-6 （3）2t^2-7t-4=0t^2-7/2t-2=0(t-7/4)^2=2+49/16=81/16,t=7/4±9/4，t=4或-1/2(4)3X^2-1=6X x...