Given how complicated the derivative,
![f'(x)=(\cos(1-x^2))/(x^2+\sqrt x)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/m6yeo9jpvuj0vsvhp6d1hald9an6hpqz5n.png)
looks, integrating it to find
seems futile, and actually not what needs to be done. You're asked to approximate
using a given point and the value of the derivative at any point. To do that, you can use a linear approximation.
![f(7)\approx f(2)+f'(2)(7-2)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/rcworitf7hcfgewlvissfnfp68bu9itje4.png)
which comes from exploiting the mean value theorem (solve for
above to see how)
Then
![f(7)\approx8+(5\cos(1-2^2))/(2^2+\sqrt2)\approx7.086](https://img.qammunity.org/2020/formulas/mathematics/middle-school/mloicztyixpwxb2wokocaloa0k4swl79nk.png)
The closest answer would be B. The reason the listed answer is so far off is because 7 is not so close to 2.