3x+4y=16 5x-6y=33 这么做?
3x+4y=16 5x-6y=33 这么做?
已知-x+3y=5,求5(x-3y)²-8(x-3y)-5的值.请附理由,为什么这么做.
{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=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
4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6
(5x+3y)(3y-5x)-(4x-y)(4y+x)=
6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5
{4/(x+y)+6/(x-y)=3 {9/(x-y)-1/(x+y)=1
3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27
5(X-3Y)-6=2X+1,3(X+Y)=4(2X-Y)+16
3分之2(X-Y)-4分之X+Y=-1,6(X+Y)-4(2X-Y)=16