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 (x + a + b + c) 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 = (x + a + b + c)(1)[(x)(x) – (0)(0)]


Δ = (x + a + b + c)(x)(x)


Δ = x2(x + a + b + c)


The given equation is Δ = 0.


x2(x + a + b + c) = 0


Case – I:


x2 = 0 x = 0


Case – II:


x + a + b + c = 0 x = –(a + b + c)


Thus, 0 and –(a + b + c) are the roots of the given determinant equation.


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