Answer:
7 + 3[tex]\sqrt{5}[/tex]
Step-by-step explanation:
Given
(2 + [tex]\sqrt{5}[/tex] )(1 + [tex]\sqrt{5}[/tex] )
Each term in the second factor is multiplied by each term in the first factor, that is
2(1 + [tex]\sqrt{5}[/tex] ) + [tex]\sqrt{5}[/tex](1 + [tex]\sqrt{5}[/tex])
Distribute both parenthesis noting that [tex]\sqrt{5}[/tex] × [tex]\sqrt{5}[/tex] = 5
= 2 + 2[tex]\sqrt{5}[/tex] + [tex]\sqrt{5}[/tex] + 5 ( collect like terms )
= 7 + 3[tex]\sqrt{5}[/tex]
