Can someone answer these questions ? thank you

Step-by-step explanation:

12a)To rationalize the denominator, multiply the denominator and numerator by √5.

b) (a+b)² = a² + 2ab + b²

(1 +√3)² = 1² + 2*1*√3 + (√3)²

= 1 + 2√3 + 3

= 4 + 2√3

a = 4 ; b =2

13) (a + b)(a - b) = a² - b²

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i hope this is what you were looking for.

see attached graph