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For what value of ‘a’ the vectors 2 i^ - 3 j^ + 4 k and a i^ + 6 j^ - 8 k are collinear?
Two vectors x→ and y→ are collinear if x→ = λ y→, where λ is a constant.Now, the vectors 2 i^ - 3 j^ + 4 k and a i^ + 6 j^ - 8 k are collinear,∴ 2 i^ - 3 j^ + 4 k = λ a i^ + 6 j^ - 8 k , where λ is a constant.⇒ 2 = λ a, - 3 = 6 λ, 4 = - 8 λ⇒ Now, - 3 = 6 λ or 4 = - 8 λ ⇒ λ = - 122 = λ a⇒ 2 = - 12 x a⇒ a = - 4
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