12題因式分解

^係2次方呀可?

1)(x+y)^ - 49
=(x+y)^ - 7^
=(x+y+7)(x+y-7)

2)81 - (x-y)^
=9^ - (x-y)^
=[9 -(x-y)][9+(x+y)]
=(9 - x+y)(9+x+y)

3)(x-y)^ - y^
=( x - y+y)(x - y - y)
=x(x - 2y)

4)(2x - y)^ - x^
=(2x - y+x)(2x - y -x)
=(3X - y)(x - y)

5)(a - b)^ - (a+b)^
=[a - b+(a+b)][a -b-(a + b)]
=(a - b+a+b)(a - b - a - b)
=2a(-2b)
= - 4ab

6)(2a+b)^ - (a - b)^
=[2a+b+(a - b)][2a+b - (a - b)]
=3a(a+2b)

7)4(2x+y)^+4(2x+y)+1
=[2(2x+y)+1]^ <------------------設(2x+y)=a , 則4a^+4a+1=(2a+1)^
=(4x+2y+1)^

8)(x - y)^ - 8(x - y)+16
=[(x - y) - 4]^ <-------------------設(x - y)=b , 則b^ - 8b+16=(b - 4)^
=(x - y - 4)^

9)(x^ - y^)+4x+4y
=(x+y)(x - y)+4(x+y)
=(x+y)(x - y+4)

10)(4x^ - y^) - 8x - 4y
=(2x+y)(2x - y) - 4(2x+y)
=(2x+y)(2x - y - 4)

11)4x^ - (4y^ - 4yz + z^)
=(2x)^ - (2y - z)^
=[2x+(2y - z)][2x - (2y - z)]
=(2x+2y - z)(2x - 2y+z)

12)(x^+6xy+9y^) - 16z^
=(x+3y)^ - (4z)^
=(x+3y+4z)(x+3y-4z)