帮忙分解下列因式1.(2x-1)(x+3)-42.(x+5)^2-3(x+5)-103.x^2-7x+12-x-4希望给详细步骤和讲解,我实在想知道怎么做!谢谢!x^2-7x+12-x-4这个是3.x^2-7x+12-x+4对不起!

Question

帮忙分解下列因式
1.(2x-1)(x+3)-4
2.(x+5)^2-3(x+5)-10
3.x^2-7x+12-x-4
希望给详细步骤和讲解,我实在想知道怎么做!谢谢!
x^2-7x+12-x-4
这个是3.x^2-7x+12-x+4
对不起!

Answer 1

1 (2x-1)(x+3)-4
=2x^2+2x-3-4
=2x^2+2x-7
=(2x+7)(x-1)
2 (x+5)^2-3(x+5)-10
可以把(x+5)看成未知数a
a^2-3a-10
=(a+2)(a-5)
=x(x+7)
3 x^2-7x+12-x-4
=x^2-8x+8
会不会题目错了?
否则
x=8±4√2/2=4±2√2
所以原式=(x+4-2√2)(x-4+2√2)
x^2-7x+12-x+4
=x^2-8x+16
=(x-4)^2