Show that x = 2 is a root of the equation and solve it completely.
Let
We need to find the roots of Δ = 0.
Recall that the value of a determinant remains same if we apply the operation Ri→ Ri + kRj or Ci→ Ci + kCj.
Applying R2→ R2 – R1, we get
Taking the term (x – 2) common from R2, we get
Applying R3→ R3 – R1, we get
Taking the term (x + 3) common from R3, we get
Applying C1→ C1 + C3, we get
Expanding the determinant along C1, we have
Δ = (x – 2)(x + 3)(x – 1)[(–3)(1) – (2)(1)]
⇒ Δ = (x – 2)(x + 3)(x – 1)(–5)
∴ Δ = –5(x – 2)(x + 3)(x – 1)
The given equation is Δ = 0.
⇒ –5(x – 2)(x + 3)(x – 1) = 0
⇒ (x – 2)(x + 3)(x – 1) = 0
Case – I:
x – 2 = 0 ⇒ x = 2
Case – II:
x + 2 = 0 ⇒ x = –3
Case – III:
x – 1 = 0 ⇒ x = 1
Thus, 2 is a root of the equation and its other roots are –3 and 1.