Q4 of 104 Page 468

Find the values of k for which k + 12, k – 6 and 3 are in GP.

To find: Value of k


Given: k + 12, k – 6 and 3 are in GP


Formula used: (i) when a,b,c are in GP b2 = ac


As, k + 12, k – 6 and 3 are in GP


⇒ (k – 6)2 = (k + 12) (3)


⇒ k2 – 12k + 36 = 3k + 36


⇒ k2 – 15k = 0


⇒ k (k – 15) = 0


⇒ k = 0 , Or k = 15


Ans) We have two values of k as 0 or 15


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