Question

Find the value of k for which the given series is AP is 4, k-1, k-2.​

Answer 1

$t3 - t2 = t2 - t1 \\ k - 2 - (k - 1) = k - 1 - 4 \\ k - 2 - k + 1 = k - 1 - 4 \\ - 1 = k - 5 \\ - 1 + 5 = k \\ k = 4$