2x²+2x-6=0用公式法
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6x²-x-12=0x=[1±√(1+4*6*12)]/12x=[1±17]/12x1=3/2,x2=-4/33x²-1=2x3x²-2x-1=0x=[2±√(4+12)
∵a=2,b=1,c=6∴Δ=1²-4×2×﹙﹣6﹚=49﹥0∴X1=﹙-1﹢√49﹚/﹙2×2﹚=3/2X2=﹙-1-√49﹚/﹙2×2﹚=2
(x+2)(2x-9)=-62x²-5x-18=-62x²-5x-12=0x={-(-5)±√[(-5)²-4×2×(-12)]}/(2×2)x=(5±11)/4x1=4
x²+2x=0a=1;b=2;c=0△=b²-4ac=4-0=4所以,x1=(-2+2)/2=0x2=(-2-2)/2=-2
²-4ac=2²-4×1×0=4则√b²-4ac=2即为-2±2/2得x1=0,x2=-2.再答:过奖过奖!再问:万分感谢,以后请多多关照了!再答:OK再问:谢谢您。再答
x²-6x+1=0判别式=36-4=32x=(6±√32)/2=3±2√22x²-x=6-x2x²=6x²=3x=±√3
1,x=[-b_+(b^2-4ac)^0.5]/2a=[6_+(6^2-4*3*-2)^0.5]/2*3=(6_+60^0.5)/6=(6+2*15^0.5)/6=1+15^0.5/3或1-15^0.
x²-2x=0x(x-2)=0x=0x=2x²-2x=0x²-2x+1=0+1(x-1)^2=1x-1=±1x=0x=2
(2x+1)(x-3)=x2x²-6x+x-3=x2x²-6x-3=0a=2,b=-6,c=-3b²-4ac=36+24=60x=(6±√60)/4=(3±√15)/2
-5±(根号3)/2
2x-3x-2=0-2=3x-2xx=-2再问:是2x的二次方不是2x再答:2x^2-3x-2=0x=2x=-1/2
x²+x-6=0(x+3)(x-2)=0x+3=0或x-2=0解得x=-3或x=23x²-6x-2=0[x-(3+√15)/3][x+(3-√15)/3=0x=(3+√15)/3或
a=9,b=6,c=1则△=b²-4ac=36-36=0所以x=(-6±0)/18所以x1=x2=1/3
令t=X^2+x,则原方程为t(t-3)-3t+8=0,因式分解为(t-2)(t-4)=0.所以得:t1=2,t2=4.即:X^2+x=2或X^2+x=4(无解,因为b^2-4ac再问:想问一下最后舍