Answer:
30 - 10[tex]\sqrt{5}[/tex]
Step-by-step explanation:
(5 - [tex]\sqrt{5}[/tex] )(5 - [tex]\sqrt{5}[/tex] )
each term in the second factor is multiplied by each term in the first factor.
5(5 - [tex]\sqrt{5}[/tex] ) - [tex]\sqrt{5}[/tex] (5 - [tex]\sqrt{5}[/tex] ) ← distribute both parenthesis
= 25 - 5[tex]\sqrt{5}[/tex] - 5[tex]\sqrt{5}[/tex] + 5 ← collect like terms
= 30 - 10[tex]\sqrt{5}[/tex]