Question

Expand using identity (3x+7) square​

Answer 1

Answer:

(3x + 7)²

(3x)² + 2(3x)(7) + (7)²      [(a+b)² = a² + 2ab + b²]

9x² + 42x + 49 is the answer

Step-by-step explanation:

Answer 2

9x² + 42x + 49

Step-by-step explanation:

(3x + 7)²

=> (3x)² + 2(3x)(7) + 7².....[using identity (a+b)² = a²+2ab+b²]

=> 9x² + 42x + 49

So,

the expansion is 9x² + 42x + 49.

Used identity :-

• (a + b)² = a² + 2ab + b²

more Identities you should remember :-

• (a - b)² = a² - 2ab + b²
• a² - b² = (a + b)(a - b)
• a² + b² = (a + b)² - 2ab or (a - b)² + 2ab

hope it helps.