x平方 25x=1900

（x-y)²=x²+y²-2xy=x²+y²+2xy-4xy=(x+y)²-4xy=7²-2[(x+y)²-x²

2x^2+x^2+4x+4+x^2+8x+16+x^2+12x+36=5x^2+24x+56=6x^2+22x+12得到：x^2-2x-44=0x1=1+3*(根号5)x2=1-3*(根号5)（根号打

x²=0.01x=-0.1,x=0.116x²-25=0x²=25/16x=-5/4,x=5/48x³=-125x³=-125/8x=-5/2

x平方-x+1=x平方-x分之6-x+1=-x分之6x-x分之6-1=0x平方-x-6=0(x-3)(x+2)=0x-3=0,x+2=0所以,x=3.x=-2

25的平方-x的平方=17的平方-（28-x）的平方x^2-(28-x)^2=25^2-17^2x^2-x^2+56x-28^2=33656x=336+78456x=1120x=20

(2-x)平方=162-x=±4x=2±4x1=6,x2=-24(x+1)平方-25=0(x-1)^2=25/4x-1=±5/2x=1±5/2x1=7/2x2=-3/2x平方-2x+1=3(x-1)^

5X²-[X²(5X²-2X)-(2X²-3X)]=5X²-(5X^4-2X^3-2X²+3X)=7X²-5X^4+2X^3-3X

x²-3x+1=0x²+1=3x同时除以xx+1/x=3(x+1/x)²=9x²+1/x²+2=9x²+1/x²=7x²

x²-（5-x）²=36-25[x+（5-x）][x-（5-x)]=115(2x-5)=1110x-25=1110x=36x=3.6

x²+y²=25x+y=7(x+y)²=49x²+y²+2xy=492xy=49-25=24(x-y)²=(x+y)²-4xy=7

由x+y=25x+y=7则(x+y)=x+y+2xy=7=492xy=(x+y)-（x+y）=49-25=24则（x-y)=x+y-2xy=25-24=1因为：x＜y所以x-y＜0即x-y=-1

x(25x-1)=0x=0或x=1/25同理

因式分解得（x-8)(x+7)=0所以x=8orx=-7

144x平方-9=0x²=9/144x=3/12或x=-3/122x平方+3x+1=0(2x+1)(x+1)=0x1=-1/2x2=-125-10x+x平方=5-xx²-9x+20

x/x(x-1)+2=2x/(x+1)1/(x-1)+2=2x/(x+1)x+1+2(x-1)(x+1)=2x(x-1)x+1+2x²-2-2x²-2x=0-x-1=0-x=1x=

解2x^2+3x=32x^2+3x-3=0△=b^2-4ac=9+24=33∴x=(-3+√33)/4或x=(-3-√33)/4(2)x^2-2x+1=25(x-1)^2=25∴x-1=±5∴x=6或

7/x(x+1)-6/(x+1)(x-1)=-1/x(x-1)两边乘以x(x+1)(x-1)得7(x-1)-6x=-(x+1)7x-7-6x=-x-12x=6∴x=3经检验：x=3是方程的解

[4(2x-1)]²-[5(x-2)]²=0(8x-4)²-(5x-10)²=0(8x-4+5x-10)(8x-4-5x+10)=0(13x-14)(3x+6)

1,整理得到y=（4+x）/（1+x）=1+3/(1+x),所以要使y为整数,1+x是3的约数,1,3,对应x为0,2,带入求y即可.2,整理为2（x-y）方+3（y-2）方+1,要使最小,x=y=2

设y=x²+x原方程即y(y-2)=-1y²-2y+1=0(y-1)²=0y-1=0y=1x²+x-1=0x=(-1±√5)/2