The value of a, for which the points (9,5),(1,2) and (a,8) are collinear, is
A
17
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B
8
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C
7
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D
71
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E
1
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Solution
The correct option is A17 Given, points (9,5),(1,2) and (a,8) are collinear. ∣∣
∣∣951121a81∣∣
∣∣=0 Applying operation R2→R2−R1,R3→R3−R1 we get ∣∣
∣∣951−8−30a−930∣∣
∣∣=0 Expanding along C3, we get −24+3(a−9)=0 ⇒3a−51=0⇒a=17.