Solving equation for a value of x

hi everyone

this is a pretty basic question but i couldnt find an answer to it

i have a 5th order polynomial function g(x) which im trying to find the slope of it at a given point x = 20

im using matlab R2020a

Answer 1

[Stephan]

You can use polyder, that calculates the derivative of a polynomial and then you can calculate the result at x=20 using polyval.

[ali koulani]

THANKS !

Answer 2

[XueHuang]

您可以使用polyder计算多项式的导数，然后可以使用polyval计算x=20时的结果.

polyval(polyder(x,a),20);就是这样的