80*(X+2)=Y 240*(X-4)=Y 怎么算呢?
微分方程 (x^2)*y"-x*y'+y=1怎么解呢?
if ( x< y ) { t=x; x=y; y=t; } 怎么理解呢?
y/x+20=2.5与y/x-20=3 问 怎么算出x和y呢
整数x,y满足方程2xy+x+y=83,则x+y怎么算
3^x=y-1的反函数怎么算呢?
y=a^x· x^a 怎么求导呢?
2x-y=8 3x+2y=5与3x+2y=1 3x-4y=-11用加减法怎么算?
{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
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