13/15X+1/3Y=48 X+Y=96

解方程组: ｛3x+2y=13 3x-2y=5 ｛x-y/3=x+y/2+1 2x-5y=9 9y=3x-(x-1),4(x+y)-(2x+4)=8y (x+2y)(x-2y)-(2x-y)的平方+(3x-y)(2x-5y)其中x=-1 y=13分之1 y(x+y)+(x-y)²-（x+y）（x-y）,其中x=-1/3,y=3 导数的计算练习题导数的计算（1）y=x^5 （2)y=sinx(3)y=1/x^3(4)y=5^√x(5)y=cosx(6)y=5^x(7)y=log3^x(8)y=lnx(9)f(x)=x^3-x^2-x+1(10)y=2x^3-3x^2+4x-1(11)y=x inx（12）y=xsinx-cosx(13)y=cosx/x(14)y=3x(x^2+2)(15)f(x)=(x-1)^2+3(x-1)(16)f(x)=1 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 2（x+y)-3(x-y)=3 ,4(x+y)+3(x-y)=15 3(x+y)-2(x-y)=11 4(x+y)+3(x-y)=9 4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11 {3(x+y)+3(y+x)=1,3(x+y)+4(y-x)=-1 (3x-y)^2+(3x+y)(3x-y),x=1,y=-2 y'=(x-y+1)/(x+y-3)通解 x-3y=2x+y-15=1 2(x+y)-3(x-y)=1 6(x+y)+(x-y)=51 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 变量x,y满足约束条件,x+y>=3,x-y>=-1,2x-y 二元一次方程 ：2(x+y)-(x-y)=3 (x+y)-2(x-y)=1 (x-y)^2+(x+y)(x-y) 其中 X =3 Y=-1