x平方加2x减6等于0-搜答案-灵鹊做题网

应该是x^2-2x+y^2+6y+10=0配方：x^2-2x+1+y^2+6y+9=0(x-1)^2+(y+3)^2=0得x=1y=-3所以x+y=-2

x^2-2x+y^2+6y+10=0(x-1)^2+(y+3)^2=0(x-1)^2=0x-1=0x=1(y+3)^2=0y+3=0y=-3x+y=1-3=-2

x^2+6x-1=0用求根公式x=(-6±√36+4)/2x=-3±√10

-10x^2+2x+3=03x^2+6x+9=03x^2+6x=-93x^2+6x-1=-10

由题意得x²+2x-1=0所以x²+2x=1所以原式=3x²+6x+4=3(x²+2x)+4=3*1+4=7

x平方减5x加2等于0

x^2+2x+y^2-6y+10=0=(x^2+2x+1)+(y^2-6y+9)=0=(x+1)^2+(y^2-6y+3^2)=0=(x+1)^2+(y-3)^2=0x=-1y=3xy=-3

这样的题以后就别问了令t=x平方加xt（t-2）=24t^2-2t-24=0（t-6）（t+4）=0t1=6.t2=-4x^2+x=6或者x^2+x=-4（无解△＜0）（x+3）（x-2）=0x1=-

x^2-2x+y^2+6y+10=0x^2-2x+1+y^2+6y+9=0(x-1)^2+(y+3)^2=0x-1=0,y+3=0x=1,y=-3(x-y)/(x+y)=4/(-2)=-2

第一个方程用十字相乘算出x=1,x=2代入第二个要求的方程,算一下38和154

x^2-3x+1=0x+1/x=(x^2+1)/x=(x^2-3x+1+3x)/x=(0+3x)/x=3x^2+1/x^2=(x+1/x)^2-2=3^2-2=7

解题思路：利用一元二次方程根的判别式求解。解题过程：解：∵x2-2x+4=0∴△=（-2）2-4×1×4=4-16=-12<0∴此方程无解最终

Δ=36-4=32x=2分之（6加减4根号2）x=3加减2根号2

6x²-7x+1=0(x-1)(6x-1)=0x=1,x=1/6再问：能详细一点吗谢谢再答：6x^2-6x-x+1=06x(x-1)-(x-1)=0(x-1)(6x-1)=0

2x^2-3x+1=0(2x-1)(x-1)=02x-1=0x=1/2x-1=0x=1

问题求什么?再问：求x加y的值再答：x^2-2x+1+y^2-6y+9=0(x-1)^2+(y-3)^2=0x=1y=32x+3y=11

2x²-3x+6=0∵a=2,b=-3,c=6b²-4ac=(-3)²-4×2×6=9-48=-39＜0∴原方程无实数根.

4x²+3x-2=0△=9+4×2×4=41x=(-3±√41)/8再问：△=9+4×2×4=41这个是哪里来的呀如果这是一道问答题那它有没有实数解，有几个解再答：△=9+4×2×4=41＞

x²+2x-2=0x²+2x+1=2+1（x+1）²=3x+1=±√3x=±√3-1x1=√3-1x2=-√3-1