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If 5+25−2\frac{\sqrt5+\sqrt2}{\sqrt5-\sqrt2}5​−2​5​+2​​​ = a + b10\sqrt{10}10​​, then which of the following is correct?
Question

If 5+252\frac{\sqrt5+\sqrt2}{\sqrt5-\sqrt2}​ = a + b10\sqrt{10}​, then which of the following is correct?

A.

a = 13\frac{1}{3}​, b = 23\frac{2}{3}​​

B.

a = 73\frac{7}{3}, b = 13\frac{1}{3}​​

C.

a = b = 13\frac{1}{3}​​

D.

a = 73\frac{7}{3}, b = 23\frac{2}{3}​​

Correct option is D

Given:

5+252=a+b10\frac{\sqrt{5} + \sqrt{2}}{\sqrt{5} - \sqrt{2}} = a + b\sqrt{10}

Formula Used:

( a + b )2 = a2 + b2 + 2ab

a2 - b2 = ( a - b ) ( a + b ) 

Solution:

5+2525+25+2=a+b10\frac{\sqrt{5} + \sqrt{2}}{\sqrt{5} - \sqrt{2}} \cdot \frac{\sqrt{5} + \sqrt{2}}{\sqrt{5} + \sqrt{2}} = a + b\sqrt{10}

(5+2)2(5)2(2)2=a+b10​\frac{(\sqrt{5} + \sqrt{2})^2}{(\sqrt{5})^2 - (\sqrt{2})^2} = a + b\sqrt{10}​​

7+2103=a+b10\frac{7 + 2\sqrt{10}}{3} = a + b\sqrt{10}​​

So,

a=73,b=23a = \frac{7}{3}, \quad b = \frac{2}{3}

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