For the function $f(x) = x^3 – 4x$, find the points where the slope of the tangent is $-1$. Use the algebraic method.
Do I need just to find zeros?
[Math] How to find the points where the slope of the tangent is $-1$
calculusderivatives
calculusderivatives
For the function $f(x) = x^3 – 4x$, find the points where the slope of the tangent is $-1$. Use the algebraic method.
Do I need just to find zeros?
Best Answer
The derivative is
$$f'(x)=3x^2-4$$
The $x$-coordinates of the points where the slope is $-1$ can be found by solving
$$3x^2-4=-1 \Leftrightarrow x^2=1$$