# MATH110/April 2017/Question 11 (c)

Also, I guess some students have difficulty in plotting ${\displaystyle 2x}$ and ${\displaystyle \cos(x)}$ accurately in the exam. So, they might not recognize that it is only intersect at once.
How about adding alternative way to show that there's only one x satisfying ${\displaystyle f'(x)=2x-\cos(x).}$? (I guess we can use ${\displaystyle f''>0}$ everywhere. )