作业帮初3数学,7道计算题! Help Me(1)4x^2+12x+9=81(2)x^2-7x-1=0(3)2x^2+3x=3(4)x^2-2x+1=25(5)x(2x-5)=4x-10(6)x^2+5x+7=3x+11
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初3数学,7道计算题! Help Me(1)4x^2+12x+9=81(2)x^2-7x-1=0(3)2x^2+3x=3(4)x^2-2x+1=25(5)x(2x-5)=4x-10(6)x^2+5x+7=3x+11
初3数学,7道计算题! Help Me
(1)4x^2+12x+9=81
(2)x^2-7x-1=0
(3)2x^2+3x=3
(4)x^2-2x+1=25
(5)x(2x-5)=4x-10
(6)x^2+5x+7=3x+11
初3数学,7道计算题! Help Me(1)4x^2+12x+9=81(2)x^2-7x-1=0(3)2x^2+3x=3(4)x^2-2x+1=25(5)x(2x-5)=4x-10(6)x^2+5x+7=3x+11
(1)4x^2+12x+9=81
4x^2+12x-72=0
x^2+3x-18=0
(x+6)(x-3)=0
x1=-6,x2=3
(2)x^2-7x-1=0
x1=(7+根号11)/2,x2=(7-根号11)/2,
(3)2x^2+3x=3
2x^2+3x-3=0
x1=(-3+根号33)/4,x2==(-3-根号33)/4
(4)x^2-2x+1=25
x^2-2x-24=0
(x-6)(x+4)=0
x1=6,x2=-4
(5)x(2x-5)=4x-10
x(2x-5)-2(2x-5)=0
(x-2)(2x-5)=0
x1=2,x2=5/2
(6)x^2+5x+7=3x+11
x^2+2x-4=0
(x+1)^2=5
x1=根号5-1,x2=-根号5-1