求详解y=tan(x+y)
问题描述：
求详解y=tan(x+y)
求隐函数的二阶导数d²y/dx²
答
你要求什么?dy/dx?1*dy/dx= sec²(x+y) *(dy/dx+1)dy/dx(1-sec²(x+y))=sec²(x+y)dy/dx(-tan²(x+y))=sec²(x+y)dy/dx=-(1+tan²(x+y))/tan²(x+y)dy/dx=-cot²(x+y)-1 d²y/d...二导。刚刚有个地方错了cot²(x+y)处理失误，重来d²y/dx²=-cot(x+y)csc(x+y){-2cot(x+y)}[1+dy/dx]=2cot²(x+y)csc(x+y)[-cot²(x+y)]=-2cot^4(x+y)csc(x+y)