x =5 y +3则x-y的值是多少-搜答案-大师作文网

2X+5Y-3=04X=6-10Y4X*32Y=(6-10Y)*32Y=192Y-320Y^2

由已知得x^2+y^2-4x-2y+5=0(x^2-4x+4)+(y^2-2y+1)=0(x-2)^2+(y-1)^2=0由于平方数都大于或等于0,所以上式成立的条件是：(x-2)^2=0,解得：x=

x+2y=2两边乘33x+6y=6所以3x+6y-1=5

2x-y/x+2y是(2x-y)/(x+2y)吧(2x-y)/(x+2y)=(2x/y-1)/(x/y+2)=(2X2/3-1)/(2/3+2)=1/3÷8/3=1/8

-2x+5y=9(1)-2x+7y=17(2)(2)-(1)2y=8y=4所以-2x+5×4=92x=11x=11/2所以x:y=11/2:4=11/8

3x-y=2x-3y+5,移项3x-y-2x+3y-5=0x+2y=5x+2y-1=5-1=4

4x+y=5A3x+2y=4BA-B=X-Y=1

解/x-2/≥0/y-3/≥0∴x-2=0,y-3=0∴x=2,y=3∴2x+3y=2×2+3×3=4+9=13

5X+7y=145①,5x+3y=105②由①－②得：4y=40,y=10③将③y=10代人①解得x=15

x+2y=1+m2x+y=3二式相加得：3(x+y)=4+m因为x+y>2,故：(4+m)/3>24+m>6m>2

由x+y=3m,x-y=9m,得x=6m代入5x+2y=4,2y=4-30m,y=2-15m

=（x-(x+y)）+（(x+2y)-(x+3y)）+...+(（x+98y）-(x+99y)）=-y*50=2*50=100

6-x+y-（y-x)²　　=6-(x-y)-(x-y)²　　=6-2-2²　　=0学习愉快!

应该是11从左向右执行,然后整个逗号表达式的值是最右边一个值#includevoidmain(){intx=3,y;intz=(x=3,y=6,x++,y++,x+y);printf("%d",

x²+y²=(x+y)²-2xy=5²-2×2=25-4=21再问：确定对？？？老师说加法的平方似乎不能那么打开再答：你好：请看(x+y)²-2xy有

(x-y)2y-2x(y-x)=(x-y)2y+2x(x-y)=2(x+y)(x-y)=2*6*4=48

2x-3y=0,所以2x=3y,x=1.5y2x+y=3y+y=4yx-y=1.5y-y=0.5y代入下式,又因为x不等于y.得：2x+y除以x-y=4y÷0.5y=8

∵x+3y=5xy∴(1/y)+(3/x)=5.5(3x+4y)=[(1/y)+(3/x)][4y+3x)≥(2+3)²=25∴3x+4y≥5∴(3x+4y)min=5再问：能不能换个方法再

是不是4x-3y=0?4x=3yy=(4/3)x所以原式=[4x-5(4/3)x]/[4x+5(4/3)x]=(-8/3)x/(32/3)x=-1/4

2x*x+4/x*x*x=2x*x/3+2x*x/3+2x*x/3+2/x*x*x+2/x*x*x>=5倍5次根下32/27x取无穷小则y趋于无穷大所以y>=10/3倍5次根号下9因为f(x)+f(-