3x^2+y^2=12 x^2/4+y^2/12=1 设直线和椭圆交于点(2cosa,2√3sina) 四边形面积为 2*2cosa*2*2√3sina=θ是小于等于45°的.为什么a=45°,θ就等于60°了呢?

(x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 已知2x-y/x+3y=2,求代数式4x-2y/x+3y减4x+12y除以2x-y 已知2x-y/x+3y=2,求代数式4x-2y/x+3y减4x+12y/2x-y的值 已知2x-y/x+3y=2,求代数式4x-2y/x+3y减4x+12y/2x-y的值 12y(x-y)^2-8(x-y)^3=? 因式分解:12xy^2(y-x)+xy^3(x-y)+4x^2y(x-y) 3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2 （x+y）/2- x-y/2=6 3(x+y)=4(x-y) x+y/3+x-y/2=6 4(x+y)-2(x-y)=40 12（x+y）^3（y-x）/【4（x+y）^2(x-y)】 2（x+y)-3(x-y)=3 ,4(x+y)+3(x-y)=15 {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 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