If one root of the quadratic equation x2 – 7x + k = 0 is 4, then find the value of k

2. If one root of the quadratic equation x² – 7x + k = 0 is 4, then find the value of k.

Sol. x² – 7x + k = 0

x = 4 is the root of given quadratic equation.

So it satisfies the given equation.

∴ (4)² – 7(4) + k = 0

∴16 – 28 + k = 0

∴–12 + k = 0

∴k = 12