6x2-7x-5.
解方程:1/x2+x +1/x2+3x+2 +1/x2+5x+6 +1/x2+7x+12 +1/x2+9x+20=5/x
求多项式3x2-6x+5与4x2+7x-6的和.
5x2+4-3x2-5x-2x2-5+6x.
(x2+5x+6)*(x2+7x+6)-3x2 (因式分解)
证明:(x3+5x2+4x-1)-(-x2-3x+2x3-3)+(8-7x-6x2+x3)的值与x无关.
1/(x2+3x+2)+1/(x2+5x+6)+1/(x2+7x+12)=1/(x+4)
已知x2+x-6=0,求代数式x2(x+1)-x(x2-1)-7的值.
先化解,再求值:【1/(x2+3x+2)+1/(x2+5x+6)+1/(x2+7x+12)】/1/(x2+9x+20),
1/(x2+x)+1/(x2+3x+2)+1/(x2+5x+6)+1/(x2+7x+12)=4/21
若3x2-x=1,则6x3+7x2-5x+2008=______.
已知3x2-x=1,求6x3+7x2-5x+2010的值______.
已知3x2-x-1=0,求6x3+7x2-5x+1999的值.