Question

数学题配方题

高分求5至10道关于配方的因式分解的题，要有详细的解答过程和答案。好的话还可以追加。

Answer 1

配方： 1. X2-2X-8=X2-2X+1-9
=(x-1)2-32
= [(x-1)+3][(x-1)-3]
= (x+2)(x-4)
2. X2+4X-5=X2+4X+4-9
=(x+2)2-32
= [(x+2)+3][(x+2)-3]
= (x+5)(x-1)

3. X2+6X+8
= （X2+6X+9）-1
=(x+3)2-12
= [(x+3)+1][(x+3)-1]
= (x+4)(x+2)
4
a2-4a-12
=a2-4a+4-16
=（a-2）2-16
=（a-2）2-42
=（a-2-4)*（a-2+4）
=(a-6)*(a+2)
5
2 y2- y -1
=(y2- y)+( y2- 1)
= y( y- 1)+ ( y+1) ( y- 1)
= ( y- 1)[ y+( y+1)]
= ( y- 1)( 2y+1)