Question

初中因式分解4道。

1.）x²-(m-5)x-3m+6
2.）x²-3x-a²+a+2
3.）x²-(2a+1)x+a²+a
4.）x²+7x+k²+k+12
要有过程。谢谢。

Answer 1

1.）x²-(m-5)x-3m+6
=x²-(m-5)x-3(m-2)
=(x+3)(x-m+2)
2.）x²-3x-a²+a+2
=x²-3x+9/4-a²+a-1/4
=(x-3/2)²-(a-1/2)²
=(x-3/2+a-1/2)(x-3/2-a+1/2)
=(x+a-2)(x-a-1)
3.）x²-(2a+1)x+a²+a
=x²-(2a+1)x+a²+a+1/4-1/4
=x²-(2a+1)x+(a+1/2)²-1/4
=(x-a-1/2)²-1/4
=(x-a-1/2+1/2)(x-a-1/2-1/2)
=(x-a)(x-a-1)
4.）x²+7x+k²+k+12
=x²+7x+49/4+k²+k+1/4-1/2
=(x+7/2)²+(k+1/2)²-1/2
=(x+7/2)²-1/4+(k+1/2)²-1/4
=(x+7/2+1/2)(x+7/2-1/2)+(k+1/2+1/2)(k+1/2-1/2)
=(x+4)(x+3)+k(k+1)

Answer 2

1、(x+3)(x-m+2)

Answer 3

1.）x²-(m-5)x-3m+6

(x+3)(x-m+2)

2.）x²-3x-a²+a+2
（x-a-1)(x-a-2)

3.）x²-(2a+1)x+a²+a

（x-a)(x-a-1)

4.）x²+7x+k²+k+12
这个符号有问题

Answer 4

1，=x*x+5x+6-mx-3m=(x+2)(x+3)-(x+3)=(x+2-m)(x+3)
2.=x(x-3)-(a-2)(a+1)
3.=x*x-2ax+a*a-(x-a)=(x-a)(x-a)-(x-a)=(x-a)(x-a-1)
4.=x*x+7x+12+k*k+k=(x+3)(x+4)+k(k+1)
ok