Question

Please answer these questions, urgent, please do not spam, step by step, I will make u brainliest please answer ​

Answer 1

•Question:

Find products using an identity.

Solution:

(a)

(2a+b)(2a-b) [Identity used: a²-b²=(a+b)(a-b)

= (2a)²-(b²)

= 2a²-b²

(b)

$(3x + \frac{1}{y} )(3x - \frac{1}{y} ) \\ = (3x {)}^{2} - ( \frac{1}{y} {)}^{2} \\ = 9 {x}^{2} - \frac{1}{ {y}^{2} } \\ = \frac{9 {x}^{2} {y}^{2} - 1 }{ {y}^{2} }$

•Question:

Solve using formulae of (a+b)² and (a-b)²

Formulae:

(a+b)²=a²+b²+2ab

(a-b)²=a²+b²-2ab

Solution:

(a)

(101)²

= (100+1)²

= (100)²+(1)²+2(100)(1)

= 10000+ 1 +200

= 10201

(b)

(99)²

= (100-1)²

= (100)²+(1)²-2(100)(1)

= 10000+1-200

=9801

(c)

(198)²

= (200-2)²

= (200)²+(2)²-2(200)(2)

= 40000+4-800

= 39204