設(shè)L為橢圓,其周長記為a,計算(2xy+3x2+4y2)ds。
求下列函數(shù)的導(dǎo)數(shù):φ(x)=e-xy2dy.
求下列函數(shù)的導(dǎo)數(shù):φ(x)=arctandy.