方程(x-3)(3x+5)-(x-1)(x+8)=-19

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方程(x-3)(3x+5)-(x-1)(x+8)=-19
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方程(x-3)(3x+5)-(x-1)(x+8)=-19
方程(x-3)(3x+5)-(x-1)(x+8)=-19

方程(x-3)(3x+5)-(x-1)(x+8)=-19
(x-3)(3x+5)-(x-1)(x+8)=-19
3x²-4x-15-(x²+7x-8)=-19
即2x²-11x+12=0
Δ=121-4*2*12=25
∴x1=(11+5)/4=4
x2=(11-5)/4=3/2

方程
(x-3)(3x+5)-(x-1)(x+8)=-19
解,得:
3x^2+5x-9x-15-(x^2+8x-x-8)+19==0
3x^2+5x-9x-15-x^2-8x+x+8+19==0
2x^2-11x+12==0
(x-4)(2x-3)==0
x1==4
或 x2==3/2...

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方程
(x-3)(3x+5)-(x-1)(x+8)=-19
解,得:
3x^2+5x-9x-15-(x^2+8x-x-8)+19==0
3x^2+5x-9x-15-x^2-8x+x+8+19==0
2x^2-11x+12==0
(x-4)(2x-3)==0
x1==4
或 x2==3/2

收起

(x-3)(3x+5)-(x-1)(x+8)=-19
3x²+5x-9x-15-x²-8x+x+8=-19
2x²-11x+12=0
(2x-3)(x-4)=0
x1=3/2 ,x2=4

(x-3)(3x+5)-(x-1)(x+8)=-19
3x^2-4x-15-(x^2+7x-8)+19==0
2x^2-11x+12=0
2(x-11/4)^2-121/8+12=0
2(x-11/4)^2-25/8=0
x=11/4±5/4
x=4或3/2