2x^2-11x+15=0 解方程用因式分解 麻烦写一下步骤 3m^2-4m-4=0和 (3x-4)^2=(4x-3)^2

2024-12-25 20:35:45
推荐回答(3个)
回答1:

2x^2-11x+15=0
十字相乘法:
(2x-5)(x-3)=0
x=5/2, 3

3m^2-4m-4=0
十字相乘法:
(3m+2)(m-2)=0
m=-2/3, 2

(3x-4)^2=(4x-3)^2
(3x-4)^2-(4x-3)^2=0
(3x-4+4x-3)(3x-4-4x+3)=0
(7x-7)(-x-1)=0
x=1, -1

回答2:

2x^2-11x+15=0
(2x-5)(x-3)=0
2x-5=0 x-3=0
x1=5/2 x2=3
3m^2-4m-4=0
(3m+2)(m-2)=0
3m+2=0 m-2=0
m1=-2/3 m2=2
(3x-4)^2=(4x-3)^2
(3x-4)^2-(4x-3)^2=0
[(3x-4)+(4x-3)][(3x-4)-(4x-3)]=0
(7x-7)(-x-1)=0
7x-7=0 -x-1=0
x1=1 x2=-1

回答3:

2x^2-11x+15=0
2(x-11/4)²=0.125
(x-11/4)²=1/16
∴x1=3,x2=5/2

3m^2-4m-4=0
3(m-2/3)²=16/3
(m-2/3)²=16/9
∴m1=2 m2=-2/3

(3x-4)^2=(4x-3)^2
9x²-24x+16=16x²-24x+9
7x²-7=0
(x-1)(x+1)=0
∴x1=1,x2=-1