初一 数学 因式分解的简单应用 请详细解答,谢谢! (23 12:14:38)

发布网友 发布时间：2024-10-24 02:38

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热心网友 时间：2024-10-27 03:13

1. x2-6x=-9
x^2-6x+9=0
(x-3)^2=0
x=3

2. (x+2)2=(2x+1)2
[(x+2)+(2x+1)][(x+2)-(2x+1)]=0
(3x+3)(-x+1)=0
3(x+1)(1-x)=0
x1=-1,x2=1

3. 9(x+3)2=(2x-5)2
[3(x+3)+(2x-5)][3(x+3)-(2x-5)]=0
(5x+4)(x+14)=0
x1=-4/5,x2=-14

4. 若a2+a-3=0,求a4+2a3-a-1的值
a4+2a3-a-1
=(a^4+a^3-3a^2)+(a^3+a^2-3a)+(2a^2+2a-6)+5
=a^2(a^2+a-3)+a(a^2+a-3)+2(a^2+a-3)+5
=5

热心网友 时间：2024-10-27 03:11

1 (x-3)平方=0
2 6（x+1）=0
3 平方后自己算，很简单
4 应该是零

热心网友 时间：2024-10-27 03:16

1.x^2-6x+9=0
(x-3)^2=0
x=3
2.(x+2)^2=(2x+1)^2
(x+2)^2-(2x+1)^2=0
(x+2+2x+1)(x+2-2x-1)=0
(3x+3)(-x+1)=0
-3(x+1)(x-1)=0
x1=-1,x2=1
3.9(x+3)^2=(2x-5)^2
[3(x+3)]^2-(2x-5)^2=0
[3(x+3)+2x-5][3(x+3)-2x+5]=0
(5x+4)(x+14)=0
x1=-4/5,x2=-14
4.a^2+a-3=0
a^2+a=3
a^4+2a^3-a-1
=a^4+a^3+a^3+a^2-a^2-a-1
=a^2(a^2+a)+a(a^2+a)-(a^2+a)-1
=3*a^2+3a-3-1
=3(a^2+a)-4
=3*3-4
=5

热心网友 时间：2024-10-27 03:14

1. x2-6x=-9
x^2-6x+9=0
(x-3)^2=0
x=3

2. (x+2)2=(2x+1)2
(x+2)^2-(2x+1)^2=0
(x+2+2x+1)(x+2-2x-1)=0
(3x+3)(1-x)=0
(x+1)(x-1)=0
x=-1或x=1

3. 9(x+3)2=(2x-5)2
9(x+3)2-(2x-5)2 =0
（3x+9)^2-(2x-5)^2=0
(3x+9+2x-5)(3x+9-2x+5)=0
(5x+4)(x+14)=0
x=-4/5或x=-14

4. 若a2+a-3=0,求a4+2a3-a-1的值
a2+a-3=0
a^2+a=3

a4+2a3-a-1
=a^4+a^3+a^3-a-1
=a^2(a^2+a)+a^3-a-1
=3a^2+a^3-a-1
=a(a^2+a)+2a^2-a-1
=3a+2a^2-a-1
=2(a^2+a)-1
=2*3-1
=5

热心网友 时间：2024-10-27 03:15

1. x2-6x=-9
X^2-6X+9=0, (X-3)^2=0, X-3=0, X=3

2. (x+2)2=(2x+1)2
(2X+1)^2-(X+2)^2=0, (2X+1+X+2)(2X+1-X-2)=0, 3(X+1)(X-1)=0
X+1=0 or X-1=0
X=-1 or X=1

3. 9(x+3)2=(2x-5)2
9(X+3)^2-(2X-5)^2= [3(X+3)]^2-(2X-5)^2=(3X+9+2X-5)(3X+9-2X+5)=(5X+4)(X+14)=0, 5X+4=0 or X+14=0

X=-4/5 or X=-14

4. 若a2+a-3=0,求a4+2a3-a-1的值

a^2+a=3,

a^4+2a^3-a-1= a^4+2a^3+a^2 - a^2-a-1=a^2(a^2+2a+1)-(a^2+a+1)
=[a(a+1)]^2-(a^2+a)-1= (a^2+a)^2 - (a^2+a) -1= 3^2-3 -1=5

热心网友 时间：2024-10-27 03:14

1.x2-6x=-9

x^2-6x+9=0
(x-3)^2=0
x1=x2=3

2.(x+2)2=(2x+1)2
(x+2)^2-(2x+1)^2=0
(x+2+2x+1)(x+2-2x-1)=0
(3x+3)(1-x)=0
x1=-1,x2=1

3.9(x+3)2=(2x-5)2
(3x+9)^2-(2x-5)^2=0
(3x+9+2x-5)(3x+9-2x+5)=0
(5x+4)(x+14)=0
x1=-4/5
x2=-14

4.若a2+a-3=0,求a4+2a3-a-1的值
因为 a2+a-3=0
所以a^2=3-a
a4+2a3-a-1
=(3-a)^2+2a^3-a-1
=2a^3+a^2-7a-1+9
=2a(3-a)+a^2-7a+8

=-a^2-a+8
=-3+8
=5