{3x+5y=19 4x-3y=6 用加减法

解方程组 3x加2y加5z=2 x-2y-z=6 4x加2y-7z=30 (x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=－2 0 求x,y分可以加. x+y/2+x-y/3=6,4(x+y)-5(x-y)=2用加减消元法解方程组 求(x加y)(2x减y)减(x加2y)(x减2y)的值,其中x等于3,y等于4求(x+y)(2x-y)-(x+2y)(x-2y)的值,其中x=3,y=4用平方差的公式计算 已知X,Y为实数,且X=根号1-3Y加根号3Y-1加2,求6Y-4X的直 x分之一加y分之一=3,求3x-4xy加3y分之x+2xy+y （x+y-5)*（x+y-5)+（x-y+3)=0 x*x-y*y 已知:3x-5y=0,求x/y,x-y/y,x-y/x 解方程组x+y（y加绝对值）=-1,3x-5y=-11 x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20 {(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20 4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6 已知X+Y=-4,怎样求二分之一X+Y-4X-Y+3X+Y-二分之三X+Y+X-Y的值二分之一乘以括号X+Y加-4乘以括号X-Y加3乘以括号X-Y负三分之二乘以括号X+Y加括号X－Y的值 （5x+3y)(3y-5x)-(4x-y)(4y+x)= {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 x+y/2+x-y/6=5 2(x+y)-3(x-y)=-2 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 （x+y）/2- x-y/2=6 3(x+y)=4(x-y)