2x+y=2 { 4x-y=1怎么算

4x方y/(x-2y)(x+2y)怎么算[x方/x-2y]-4x方y/(x-2y)(x+2y)=? X^2-2XY+Y^2-X+Y-2=0怎么算等于(x-y-2)(x-y+1)? 二元一次方程(x+y)/2+(x-y)/3=6,4(x+y)-5(x-y)=2怎么算 matlab画二元函数图像z = (x/(x+y) + 1.96*1.96/(2*(x+y)) - 1.96 * ((x/(x+y)*(1-x/(x+y))+1.96*1.96/(4*(x+y)))/(x+y))^0.5)/(1+1.96*1.96/(x+y))该怎么画 X^2Y+Y=X^怎么转换成X^=1-Y分之Y x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 x^2-4Y^2+X+3Y-1=0 2X-Y-1=0 怎么算 |x-y+2|=|x+y+2|怎么算? x²-4y²+(x-2y) =(x+2y)(x-2y)+(x+2y) 接下来还怎么算? (x/y)2-(x/y)=1怎么解? {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 对于(y一撇）y`=y/x(y-1)求导,我求的结果是y``=-y^2-y`x+y/x^2(y-1)^2 怎么不对啊,我的求导过程是：y`x(y-1) - [x(y-1)]` y y`xy-y`x-(y-1+xy`)y -y^2-y`x+yy``=-------------------------=----------------------=-----------------x^2 (y-1 2x-y=8 3x+2y=5与3x+2y=1 3x-4y=-11用加减法怎么算? x^2-4xy+3y^2=（x-3y)(x-y)x^2-4xy+3y^2 怎么分解成（x-3y)(x-y) 2x-y=-1怎么算 y'=x+2y+1/2x+4y-1这个微分方程怎么解啊? [(2X+Y)*(2X+Y)-Y(Y+4X)]/2X 怎么算? (x-y)^4·(x-y)-2(y-x)³·（y-x)²怎么算,