Question

Find the value of c that completes the square.
p^2-20p+c

Answer 1

(-20/2)^2
-10^2
100=c

Answer 2

in general, you have;
\[p^2 +bp + c = (p+ \frac{b}{2})^2\]
so
\[c = (\frac{b}{2})^2\]
here b = -20