1.

If x(3 – √7) = y(3 + √7) = 2, find the value of (x + y)/2?1. 122. 23. 64. 3

Answer» Correct Answer - Option 4 : 3

Given:

x(3 – √7) = y(3 + √7) = 2

So y(3 + √7) = 2

And x(3 – √7) = 2

Concept:

From the given equations, calculate the value of ‘x’ and ‘y’.

Calculation:

∵ x(3 – √7) = 2

⇒ x = 2/(3 – √7)     ----(1)

∵ y(3 + √7) = 2

⇒ y = 2/(3 + √7)     ----(2)

From (1) and (2);

⇒ x + y = [2/(3 – √7)] + [2/(3 + √7)]

⇒ [2(3 + √7) + 2(3 – √7)]/[(3 – √7)(3 + √7)]

⇒ (6 + 2√7 + 6 – 2√7)/[(3)2 – (√7)2]

⇒ 12/(9 – 7)

⇒ 12/2 = 6

∴ (x + y)/2 = 6/2 = 3


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