### Home > CALC > Chapter Ch3 > Lesson 3.2.3 > Problem 3-77

3-77.

This is Ana's Definition of the Derivative:

Observe that *x*^{3} + *x* = 30 when *x* = 3.

*f*(*x*) = *x*^{3} + 3

*a* = 3

Notice that *f*(3) = 3³ + 3 = 30, which confirms that equation of *f*(*x*) is correct.

*f*(*x*) = *x*³ + *x* *f* '(*x*) =_______________________*f* '(3) =__________

You just avoided a lot of Algebra!