①2(x+3)(x-3)=x²+(x-1)(x+1)+2x

来源：学生作业帮编辑：作业帮分类：数学作业时间：2024/05/11 03:20:38

①2(x+3)(x-3)=x²+(x-1)(x+1)+2x
②5X+6(3X+2)(3X-2)=54(X-1/3)(X+1/3)+2
③已知a-b=3,ab=1.求（a+b）²的值
④x+y=3,xy=-2,求x²+y²的值

解
2(x+3)(x-3)=x²+(x-1)(x+1)+2x
2(x²-9)=x²+x²-1+2x
2x²-18=2x²-1+2x
即2x=-17
x=-17/2
5x+6(3x+2)(3x-2)=54(x-1/3)(x+1/3)+2
5x+6(9x²-4)=54(x²-1/9)+2
5x+54x²-24=54x²-6+2
5x=20
x=4
a-b=3,ab=1
(a+b)²
=(a-b)²+4ab
=3²+4×1
=13
x+y=3,xy=-2
x²+y²
=(x+y)²-2xy
=3²-2×(-2)
=13
再问：分解因式：（x²+4）²-16x²
再答：解 (x²+4)²-16x² =(x²+4)²-(4x)² =(x²+4-4x)(x²+4+4x) =(x-2)²(x+2)²

①2(x+3)(x-3)=x²+(x-1)(x+1)+2x x^5+x^4 = (x^3-x)(x^2+x+1)+x^2+x x-1)(X-2)(x-3)...(x-50)+x(x-2)(X-3)...(X-50)+...+x(x-1)(x-2) 解方程x/(x-2)=2x/(x-3)+(1-x)/(x-5x+6) x^4+x^3+x^2+x+1=0,x^2006+x^2005+x^2004+x^2003+x^2002 x+2/x+1-x+3/x+2-x+4/x+3+x+5/x+4 (x+1-1/1-x)÷(x-x²/x-1) (x-4/x-x-6+ x+2/x-3)÷x+1/x-3 1+x+x^2+x^3+.+x^99+x^100 |X-1|+|X-2|+|X-3|+|X-4|+|X-5|+|X-6|+|X-7|+|X-8|+|X-9|+|X-10| 6x+(2x²-3x)-(x²-1) （2x²-2x+3)(-x³+x-1) f(x-1)=x^2-2x+3(x