Assertion :consider the determinant Δ=∣∣
∣
∣∣a1+b1x2a1x2+b1c1a2+b2x2a2x2+b2c2a3+b3x2a3x2+b3c3∣∣
∣
∣∣=0, where xi,yi,zi∈R(i=1,2,3),x∈R. The values of x satisfying Δ=0 are x=1,−1. Reason: If ∣∣
∣∣a1b1c1a2b2c2a3b3c3∣∣
∣∣=0, then Δ=0.
A
Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
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B
Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
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C
Assertion is correct but Reason is incorrect
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D
Assertion is incorrect but Reason is correct
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Solution
The correct option is B Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion Δ=∣∣
∣
∣∣a1+b1x2a1x2+b1c1a2+b2x2a2x2+b2c2a3+b3x2a3x2+b3c3∣∣
∣
∣∣=0 ⇒∣∣
∣
∣∣a1a1x2+b1c1a2a2x2+b2c2a3a3x2+b3c3∣∣
∣
∣∣+∣∣
∣
∣∣b1x2a1x2+b1c1b2x2a2x2+b2c2b3x2a3x2+b3c3∣∣
∣
∣∣=0 ⇒∣∣
∣
∣∣a1a1x2c1a2a2x2c2a3a3x2c3∣∣
∣
∣∣+∣∣
∣∣a1b1c1a2b2c2a3b3c3∣∣
∣∣+∣∣
∣
∣∣b1x2a1x2c1b2x2a2x2c2b3x2a3x2c3∣∣
∣
∣∣+∣∣
∣
∣∣b1x2b1c1b2x2b2c2b3x2b3c3∣∣
∣
∣∣=0 ⇒x2∣∣
∣∣a1a1c1a2a2c2a3a3c3∣∣
∣∣+∣∣
∣∣a1b1c1a2b2c2a3b3c3∣∣
∣∣+x4∣∣
∣∣b1a1c1b2a2c2b3a3c3∣∣
∣∣+x2∣∣
∣∣b1b1c1b2b2c2b3b3c3∣∣
∣∣=0 ⇒(1−x4)∣∣
∣∣a1b1c1a2b2c2a3b3c3∣∣
∣∣=0 ⇒x=1,−1 Also, if ∣∣
∣∣a1b1c1a2b2c2a3b3c3∣∣
∣∣=0 Then Δ=0