Solve the following determinant equations:
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 C1→ C1 + C2, we get
Applying C1→ C1 + C3, we get
Taking the term (3x – 2) common from C1, we get
Applying R2→ R2 – R1, we get
Applying R3→ R3 – R1, we get
Expanding the determinant along C1, we have
Δ = (3x – 2)(1)[(3x – 11)(3x – 11) – (0)(0)]
⇒ Δ = (3x – 2)(3x – 11)(3x – 11)
∴ Δ = (3x – 2)(3x – 11)2
The given equation is Δ = 0.
⇒ (3x – 2)(3x – 11)2 = 0
Case – I:
3x – 2 = 0
⇒ 3x = 2
Case – II:
(3x – 11)2 = 0
⇒ 3x – 11 = 0
⇒ 3x = 11
Thus, and
are the roots of the given determinant equation.