Answer :
Let's solve the equation; to do this we can use the general formula for quadratic equations:
[tex]x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}[/tex]For this equation we have a=4, b=28 and c=49; plugging these values in the general formula we have:
[tex]\begin{gathered} c=\frac{-28\pm\sqrt{28^2-4(4)(49)}}{2(4)} \\ =\frac{-28\pm\sqrt{0}}{8} \\ =-\frac{28}{8} \\ =-\frac{7}{2} \end{gathered}[/tex]Therefore, c=-7/2