Question

几道因式分解的题!!!!!!!!!!!!明天就撤了！！！

1/2(a^2＋4)^2-8a^4

2a^2+7a-15

(a^2+2a)^2-47(a^2+2a)-48

-a^3+8

a^3+2a^2+2a+1

(X^2-x)^2-9x^2+9x+14

最后两道选答
x^2+xy-6y^2-x+7y-2

X^3-3x^2+4

能答几道是几道吧
那一楼和四楼谁对啊

Answer 1

1/2(a^2＋4)^2-1/2(4a^2)^2 提出1／2后很容易了

15拆为－3和5

把8写成2的三次方

（a^3＋1）+2（a^2+a）以后很简单了

＝x^2×(x-1)^2-9x（x-1）+14 分解x＾2为x×x，14分解为－2和－7

Answer 2

1.1/2(a^2＋4)^2-8a^4
=1/2[(a^2+4)^2-(4a^2)^2)
=1/2(a^2+4+4a^2)(a^2+4-4a^2)
=1/2(5a^2+4)(4-3a^2)
=1/2(5a^2+4)(2+√3a)(2-√3a)
2.2a^2+7a-15
=(2a-3)(a+5)
3.(a^2+2a)^2-47(a^2+2a)-48
=(a^2+2a-48)(a^2+2a+1)
=(a+8)(a-6)(a+1)^2
4.-a^3+8
=(2-a)(4+2a+a^2)
5.a^3+2a^2+2a+1
=(a^3+1)+2a(a+1)
=(a+1)(a^2-a+1)+2a(a+1)
=(a+1)(a^2-a+1+2a)
=(a+1)(a^2+a+1)
6.(X^2-x)^2-9x^2+9x+14
=(x^2-x)^2-9(x^2-x)+14
=(x^2-x-2)(x^2-x-7)
=(x-2)(x+1)[x-(1+√29)/2][x-(1-√29)/2]
7.x^2+xy-6y^2-x+7y-2
=(x+3y)(x-2y)-2x+4y+x+3y-2
=(x+3y-2)(x-2y)+x+3y-2
=(x+3y-2)(x-2y+1)
8.X^3-3x^2+4
=x^3+1-3(x^2-1)
=(x+1)(x^2-x+1)-3(x+1)(x-1)
=(x+1)(x^2-x+1-3x+3)
=(x+1)(x^2-4x+4)
=(x+1)(x-2)^2

Answer 3

1/2(a^2＋4)^2-8a^4
=(a^4+16+8a^2-16a^4)/2=(16+8a^2-15a^4)/2=(4+5a)(4-3a)/2
2a^2+7a-15
=(2a-3)(a+5)

(a^2+2a)^2-47(a^2+2a)-48
=[(a^2+2a)-48][(a^2+2a)+1]=(a+8)(a-6)(a+1)^2

-a^3+8
=(2-a)(4+2a+a^2)

a^3+2a^2+2a+1
=(a+1)a^2+(a+1)^2=(a+1)(a^2+a+1)

(x^2-x)^2-9x^2+9x+14
=[(x-1)x]^2-9(x-1)x+14=[(x-1)x-2][(x-1)x-7]=(x^2-x-2)[x^2-x-7]=(x-2)(x+1)(x^2-x-7)

最后两道选答
x^2+xy-6y^2-x+7y-2
=(x+3y)(x-2y)-2x+4y+x+3y-2 =(x+3y-2)(x-2y)+x+3y-2=(x+3y-2)(x-2y+1)

x^3-3x^2+4
=x^2(x-2)-(x-2)(x+2)=(x-2)(x^2-x-2)=(x+1)(x-2)^2

Answer 4

2a^2+7a-15=(2a-3)(a+5)
-a^3+8=(2-a)(4+2a+a^2)
a^3+2a^2+2a+1=(a^3+1)+2a(a+1)=(a+1)(a^2-2a+1)+2a(a+1)=(a+1)(a^2+1)
只能做这几道了

Answer 5

一楼的对的
楼主没看见是把1/2提出来了吗?
怎么看题目的啊...