Question

for what value of k will K+9,2k-1 and 2k+7 be the consecutive terms of an A. P.

Answer 1

Remember if a,b & c are consecutive terms of an AP

then b = a+c/2

 so, 2k-1 = k+9 + 2k+7/2
       2k-1 = 3k+16/2
       4k-2 = 3k+16
        k = 18

Answer 2

Answer:

k + 9 , 2k - 1 and 2k + 7 are in AP ( Given )

therefore, a² - a¹ = a³ - a²

a¹, a² , a³ are the 3 consecutive terms

=> ( 2k - 1 ) - ( k + 9 ) = ( 2k + 7 ) - ( 2k - 1 )

=> k - 10 = 8

=> k = 18