SSC CGL 2022 PYQ — Question 33

SSC CGL Tier II - Quant - 3 Feb 2022 • Quantitative Aptitude • Q33

If 26−7314+53=b+a311,b>0\frac{\sqrt{26-7\sqrt{3}}}{\sqrt{14+5\sqrt{3}}}= \frac{b+a\sqrt{3}}{11}, b>0 then what is the value of (b−a)\sqrt{(b-a)}?

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Correct answer: A

Explanation

The correct answer is option 1 i.e. 5.

26−7314+53=b+a311\frac{\sqrt{26-7\sqrt{3}}}{\sqrt{14+5\sqrt{3}}}= \frac{b+a\sqrt{3}}{11}

On rationalization of the LHS part we get,

26−7314+53×14−5314−53\frac{\sqrt{26-7\sqrt{3}}}{\sqrt{14+5\sqrt{3}}} \times \sqrt{\frac{14-5\sqrt{3}}{14-5\sqrt{3}}}

364−1303−983+105196−75\frac{\sqrt{364 - 130\sqrt{3} - 98\sqrt{3}+105}}{\sqrt{196 - 75}} = b+a311\frac{b+a\sqrt{3}}{11}

469−228311=b+a311\frac{\sqrt{469 - 228 \sqrt3}}{11} = \frac{b+a\sqrt{3}}{11}

On squaring both sides we get,

469 - 2283\sqrt3 = b2 + 3a2 + 2ab3\sqrt3.

(19)2 + 3(-6)2 + 2 × 19 × (-6) = b2 + 3a2 + 2ab3\sqrt3.

on comparing we get,

a = -6 and b = 19,

(b−a)\sqrt{(b-a)} = (19−(−6)\sqrt{(19-(-6)} = 5.