Question

It is given that -3 is one of the roots of the quadratic equation x square -4x-h=0.find the value of h

Answer 1

Since -3 is one of the roots, that means it would satisfy the equation.

x^2 - 4x - h = 0,    substitute x = -3.

(-3)^2 -4(-3) - h = 0
9  +  12  -  h      = 0
21 - h = 0
21 =  h.
h  = 21.
That's the value of h.  Cheers.