Question

solvethe sum using the identity

(3a + 7b)^2 using (9 + b)^2 = 9^2+ 2ab + b^2​

Answer 1

Correct Question:-

➡ Expand (3a + 7b)² using identity.

Solution:-

(3a + 7b)²

= (3a)² + (7b)² + 2×(3a)×(7b)

= 9a² + 21b² + 42ab

= 9a² + 42ab + 21b²

Hence, the expanded form is 9a² + 42ab + 21b²

Identity used:-

➡ (a + b)² = a² + 2ab + b²

Other Identities:-

➡ (a - b)² = a² - 2ab + b²

➡ a² - b² = (a + b)(a - b)

➡ (a + b)³ = a³ + 3a²b + 3ab² + b²

➡ (a - b)³ = a³ - b³ - 3a²b + 3ab²

Answer 2

Answer:

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