搜搜考试网X+Y=158X+4Y=72X+Y=15Y=15-X代入8X+4Y=728X+4(15-X)=728X+60-4X=72
X+Y=158X+4Y=72X+Y=15Y=15-X代入8X+4Y=728X+4(15-X)=728X+60-4X=72
x-y+5x-4x= ?
y=x+4/x (x
已知2x+2y=-8,4x+y=15求（x-y)^-(3x+2y)^
[(x+2y)(x-2y)-(x-2y)^2+8y(x+y)]除以4x=
x+2x+4y=4 x+2y=2 用代入法解
{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1
{3(x+y)+3(y+x)=1,3(x+y)+4(y-x)=-1
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
3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27
4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6