Question

find c in the equation x²-4x+c=0 if it is known that the sum of square of the roots is equal to 16

Answer 1

$$\begin{gathered} x^2-4x+c=0 \\ therootsofthisequationx=2\pm \sqrt{4-c} \\ now(2+\sqrt{4-c}{)}^2+(2-\sqrt{4-c}{)}^2=16 \\ solvingthisequationwecanwrite \\ c=0\left[ANS\right] \end{gathered}$$