Answer
The given set of values is wrong as $c=10$, not $-10$.
Work Step by Step
RECALL:
The standard form of a quadratic equation is $ax^2+bx+c=0$
Write the given quadratic in equation in standard form to obtain:
$x^2=-10
\\x^2+10=-10+10
\\x^2+10=0$
The quadratic equation above has:
$a=1, b=0, c=10$
Thus, in the given set of values, the value of $c$ must be $10$ and not $-10$.