求(2-x)(3-x)的x 2极限-搜答案-百度作业网

∵x2+x-1=0，∴x2+x=1，2x3+3x2-x=2x（x2+x）+x2-x=2x+x2-x=x2+x=1．

解题思路：由完全平方公式可求解题过程：varSWOC={};SWOC.tip=false;try{SWOCX2.OpenFile("http://dayi.prcedu.com/include/rea

x^2+3x-2＝0,x(x+3)=2,∴(2x-4)╱(x^2+6x+9)÷（x-3）×(x^2-9)╱(2x-x^2)=2(x-2)/(x+3)^*1/(x-3)*(x+3)(x-3)/[x(2-

x^2-3x+2=0(x-2)(x-1)=0x=2或x=1当x=2时x^2+1/x^2=2^2+1/2^2=4+1/4=17/4当x=1时x^2+1/x^2=1^2+1/1^2=1+1=2

由条件左右除以x,得x+1/x=3平方得：x2+1/x2+2=9所以x2+1/x2—2=5所求值为根号5

等式两边同除以xx+3+1/x=0x+1/x=-3x²+1/x²+2x+2/x=(x+1/x)²-2+2(x+1/x)=(-3)²-2+2(-3)=9-2-6=

y=x2+2x+1/(x2+2x+3)=(x+1）2/(x2+2x+3)当分母一定时,分子越小越好(x2+2x+3)=（x+1）2+2永远大于零当（x+1）2越小越好而X=-1时y=x2+2x+1/(

（-3x2）（x2-2x-3）+3x（x3-2x2-3x）+2005，=-3x4+6x3+9x2+3x4-6x3-9x2+2005，=2005，∴无须将x=2005代入，无论x取何值，该代数式都等于2

X^2-5x=14->x=-2或x=72x^2-x-2x+1-[x^2+2x+1]+1=x^2-5x+1=15

答：x²-5x=3(x-1)(2x-1)-x(x+3)+15/(x²-3)=2x²-3x+1-x²-3x+15/(5x)=x²-5x-x+1+3/x=

由2x^2-3x+4>=0得x∈R,由x^2-2x>=0得x=2,因此函数定义域为（-∞,0]U[2,+∞）,1、在区间（-∞,0]上,由于2x^2-3x+4=2(x-3/4)^2+23/8,开口向上

x（x-1）-（x2-y）=-3x2-x-x2+y=-3-x+y=-3所以x-y=3所以原式=(x-y)2=9

∵x^2+3x+5=7∴x^2+3x=23x^2+9x+2=3(x^2+3x)+2=3×2+2=8

解题思路：完全平方公式解题过程：varSWOC={};SWOC.tip=false;try{SWOCX2.OpenFile("http://dayi.prcedu.com/include/readq.

原式=2x2-1，当x=-3时，原式=2×（-3）2-1=17．

亲,我终于看会了,我不是学霸,请叫我学渣,过程我写纸上了,先采后传答案,不用谢,我是雷锋.再问：传吧再问：？

y=(x^2-2x-3)/2x^2+2x+1,x^2-2x-3=2yx^2+2yx+y(2y-1)x^2+(2y+2)x+y+3=0(2y+2)^2-4(2y-1)(y+3)>=0-4=

(x2-3x-10)/(x2-2x)>0等价于(x2-3x-10)(x2-2x)>0x(x+2)(x-5)(x-2)>0(x+2)x(x-2)(x-5)>0所以x>5或0

你好x²+3x-1=0两边同除以xx+3-1/x=0x-1/x=-3两边平方得x²+1/x²-2=9x²+1/x²=11x²+1/x