X^2+3X-126=0求解
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X^2+3X-126=0求解X^2+3X-126=0求解X^2+3X-126=0求解X^2+3X-126=0X^2+3X+9/4-9/4-126=0(X+3/2)^2=126+9/4(X+3/2)^2
X^2+3X-126=0求解
X^2+3X-126=0求解
X^2+3X-126=0求解
X^2+3X-126=0
X^2+3X+9/4-9/4-126=0
(X+3/2)^2=126+9/4
(X+3/2)^2=513/4
X+3/2=(3/2)根号57
或 X+3/2=(-3/2)根号57
解得:X=(3/2)根号57-3/2 或者X=(-3/2)根号57-3/2
x={-3±√[(3^2-4*1*(-126)]}/2
=[-3±√513]/2
=[-3±√(3*3*57)]/2
=[-3±3√57]/2
=-3/2±3√57/2