Question

if a= 5-2
$\sqrt{5}$
then find a^2​

Answer 1

Step-by-step explanation:

a = 5-2√5

then,

squaring on both sides

a²= (5-2√5)²

[since (a-b)² = a²-2ab+b²]

= 5² - (2 x 5 x 2√5) + (2√5)²

=25 - 20√5 + (4 x 5)

= 25 - 20√5 + 20

=45 - 20√5