Question

If 5 a - 2b = 7 and a b = 2 . Find the value of (5a + 2 b )2​

Answer 1

Answer:

129

Step-by-step explanation:

(5a - 2b)2 = 25a^2 +4b^2 - 20ab =7^2

              = 25a^2 +4b^2 = 49 + 20ab

              = 25a^2 +4b^2 = 49 + (20x2)

              = 25a^2 +4b^2 = 89

(5a+2b)2 = 25a^2 +4b^2 + 20ab = 89 + 20ab

               = 25a^2 +4b^2 + 20ab = 89 + 40

               = 25a^2 +4b^2 + 20ab = 129

Hence (5a+2b)2 = 129