State whether k is the root of the given equation y2 – (k – 4)y – 4k = 0.


4. State whether k is the root of the given equation y2 – (k – 4)y – 4k = 0.

Sol. y2 – (k – 4)y – 4k = 0.

By putting y = k in L.H.S. we get

L.H.S. = (k)2 – (k – 4)(k) – 4k

= k2 – (k2 – 4k) – 4k

= k2 – k2 + 4k – 4k

= 0

= R.H.S.

L.H.S. = R.H.S.

Thus equation is satisfied.


So, k is the root of the given quadratic equation.