Question

Can someone answer these questions ? thank you

Answer 1

Explanation:

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

`(15)/(√(5))=(15*√(5))/(√(5)*√(5))\\\\=(15√(5))/(5)\\\\=3√(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

`((6-√(5))(6+√(5)))/(√(31))=(6^(2)-(√(5))^(2))/(√(31))\\\\ =(36-5)/(√(31))\\\\=(31)/(√(31))\\\\=(31*√(31))/(√(31)*√(31))\\\\=(31√(31))/(31)\\\\=√(31)`