Can you help how to write this?

Question

Please can you help me with this ,how can i write this one?

Answer 1

try the below code

$$\left.\frac{dy}{dx}\right|_{x=-1}=-5$$

Answer 2

Your post has the vertical line extended well below the baseline. If this is important to you, try this code:

\[\frac{dy}{dx}\,{\rule[-3.5ex]{.1ex}{7.0ex}\,}_{x=-1}=-5\]

This allows you manual control of the vertical line. In the code above, the -3.5 controls the depth of the line, the .1 controls the thickness of the line and the 7.0 controls the total height of the line.