Question

初一数学题..

1.(x^4-x^2-2x-1)/(x^2-x-1)
2.将多项式3x^2-4x+7表示成a(x+1)^2+b(x+1)+c的形式
3.分解因式:(6x+7)^2(3x+4)(x+1)-6

Answer 1

1.(x^4-x^2-2x-1)/(x^2-x-1)
=(x^4-(x+1)^2)/(x^2-x-1)
=(x^2+(x+1))(x^2-(x+1))/(x^2-x-1)
=(x^2+x+1)(x^2-x-1)/(x^2-x-1)
=(x^2+x+1)
2.将多项式3x^2-4x+7表示成a(x+1)^2+b(x+1)+c的形式
3x^2-4x+7
=3x^2+6x+3-10x+4
=3x^2+6x+3-10x-10+14
=3(x+1)^2-10(x+1)+14

3.分解因式:(6x+7)^2(3x+4)(x+1)-6
(6x+7)^2(3x+4)(x+1)-6
=(36x²+84x+49)(3x²+7x+4)-6
令a=3x²+7x+4
则36x²+84x+49=12a+1
∴原式=a(12a+1)-6
=12a²+a-6
=(3a-2)(4a+3)
=(9x²+21x+10)(12x²+28x+19)
=(3x+2)(3x+5)(12x²+28x+19)

追问

不好意思呢~还有一道漏掉叻..
给你积分哈..
a与b的和除以a与2b的差的平方所得的商的相反数为_____.

追答

a与b的和除以a与2b的差的平方所得的商的相反数为
-(1+b/a-2b)^2