Question

求导数或者微分

Answer 1

1、e^(2x+y)-cos(xy)=e-1
显然x=0时，y=1
求导数得到
e^(2x+y) *(2+dy/dx)+sin(xy) *(y+dy/dx)=0
代入x=0，y=1，即e*(2+dy/dx)=0，所以dy/dx= -2
即此时dy= -2dx
2、lny=1/4*[ln(x+1)+ln(x+2)-ln(x+4)-ln(x+5)]
求导数得到y'/y=1/4 *[1/(x+1)+1/(x+2)-1/(x+4)-1/(x+5)]
于是dy/dx=1/4 *[1/(x+1)+1/(x+2)-1/(x+4)-1/(x+5)] *y

追问

大哥 答案不对题