n2 + 4n = 0, n = 0, – 2, – 4

(v) n² + 4n = 0, n = 0, – 2, – 4

Sol. a) By putting n = 0 in L.H.S. we get

L.H.S. = (0)² + 4(0)

= 0 + 0

= 0

= R.H.S.

∴ L.H.S. = R.H.S.

Thus equation is satisfied.

So, 0 is the root of the given quadratic equation.

b) By putting n = –2 in L.H.S. we get

L.H.S. = (– 2)² + 4(– 2)

= 4 – 8

= – 4

≠ R.H.S.

∴ L.H.S. ≠ R.H.S.

Thus equation is not satisfied.

So, –2 is not the root of the given quadratic equation.

c) By putting n = –4 in L.H.S. we get

L.H.S. = (– 4)² + 4(– 4)

= 16 – 16

= 0

= R.H.S.

∴ L.H.S. = R.H.S.

Thus equation is satisfied.

So,  – 4 is the root of the given quadratic equation.