"Solve" action is used to compute roots of an equation. If the action is not disabled by your instructor, you can use this action to compute the roots (values that satisfy the equation) of an equation immediately. Below you can find the screenshots that explain how this action is used. 

Once the action is applied the equation, the roots of the equation will be listed immediately.  

Hope this helps. Please never hesitate to contact us here, in case you have questions or concerns related to this action.