Solution
Correct Answer: Option B
আমরা জানি,
(a + b + c)² = a² + b² + c² + 2(ab + bc + ca)
বা, (a + b + c)² = a² + b² + c² + 2(ab + bc + ca)
বা, (9)² = 29 + 2(ab + bc + ca)
বা, 81 = 29 + 2(ab + bc + ca)
বা, 81 - 29 = 2(ab + bc + ca)
বা, 52 = 2(ab + bc + ca)
বা, ab + bc + ca = 52/2 = 26