a,b,c,x = symbols("a b c x")

my_eq = Eq(a*x**2+b*x+c,0)

solve(my_eq,x)

Out[12]: [(-b + sqrt(-4*a*c + b**2))/(2*a), -(b + sqrt(-4*a*c + b**2))/(2*a)]

t=Derivative(sin(x),x) #t=sin(x)

print(t)

t.doit() #求导

Derivative(sin(x), x)

Out[13]: cos(x)

diff(sin(2*x),x)

Out[18]: 2*cos(2*x)

sin(2*x).diff(x)

Out[19]: 2*cos(2*x)

diff(sin(2*x),x,2)  #2阶导

Out[20]: -4*sin(2*x)

diff(sin(2*x),x,3)   #3阶导

Out[21]: -8*cos(2*x)

diff(sin(x*y), x,2,y,3)

Out[22]: x*(x**2*y**2*cos(x*y) + 6*x*y*sin(x*y) - 6*cos(x*y))