help with #3 pls and #2 thank u2) Determine the points at which the graph of the function has a horizontal tangent linef (x) = x^2 ??????- x-3

Need Help? Read It Watch it 3. [-/3 Points] DETAILS LARCALCET7 3.3.019. Find f'(x) and f'(c). Function Value of c ((x) = x2 - 4 X - 7 C = 1 f' (x ) = F' ( C ) = Need Help? Read It 4. [1.5/1.5 Points] DETAILS PREVIOUS ANSWERS LARCALCET7 3.3.027.MI