Question

if a = 5 - 2 root 5 then find a square​

Answer 1

Answer:

given a = 5 - 2√5

then, (a)^2 = (5-2√5)^2

[ (a-b)^2 = a^2 + b^2 - 2ab ]

=> (a)^2 = (5)^2 + (2√5)^2 - 2(5)(2√5)

= 25 + 20 - 20√5

= 45 - 20√5

Answer 2

Answer:

45-20√5

Step-by-step explanation:

a = 5-2√5

then

a²= (5-2√5)²

[using (a-b)² = a²-2ab+b²]

= 5² - (2)(5)(2√5) + (2√5)²

=25 - 20√5 + (4)(5)

= 25 - 20√5 + 20

=45 - 20√5

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