(2√7 +√27)(√28-3√3) anwser in radical form

Question

Hi I'm a 10 year old plz help me 

Answer 1

The STRUCTURE of this is (a+b)(a-b) which equals a²-b² but it is disguised because the second factor, in parentheses, can be simplified: (√28-3√3) = (2√7 - 3√3) and the first factor can also be simplified:

(2√7 +√27) = (2√7 +3√3).

 

now we have a = 2√7 and b = 3√3) and their squares are 28 and 27, so the value of this product is ONE.

 

 

Answer 2

First simplify each factor

(2√7 + √27) = (2√7 + 3√3)  

(√28 - 3√3) = (2√7 - 3√3)

(2√7 + 3√3)(2√7 - 3√3) =

(2)(2)(√7)(√7) + 3(√3√)(2)(√7) - 3(√3√)(2)(√7) - (3)(3)(√3)(√3)  =

4(7) - 9(3)     middle two terms add to zero

 

Finish?