If $x=4$ is a root of the quadratic equation $x^2+ax-5=0$, find the value of $a$

Step-by-step solution

1. Substitute $x=4$ into the equation: $4^2+4a-5=0\to 16+4a-5=0$.
2. Simplify: $4a+11=0$.
3. Solve for $a$: $4a=-11\to a=-11/4$.
4. Therefore $a=-\frac{11}{4}$.

Concept tested: Determining a parameter from a known root

Published 7 October 2026 · How this solution was prepared and checked