If x = 2+\sqrt 5 and y = 2-\sqrt 5, find the value of (x ^2 + y^ 2 ):

Powers and Roots Practice Test 1

Question : 6 of 40

Marks: +1, -0

x = 2+√ 5

and

y = 2-√ 5

, find the value of

(x ^2 + y^ 2 ):

Solution:

x = 2+√ 5

and

y = 2-√ 5

,
∴

(x ^2 + y^ 2 ) =(2+√5)^2+(2-√5)^2

=4+5+4√5+4+5-4√5

=18

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