CAT 2024 Quant was dominated by Algebra followed by Arithmetic. In Arithmetic, the questions were dominated by topics like Speed-time-distance, Mixture and Alligations. This year, there was a surprise. The questions from Geometry were relatively on the lower side as compared to the previous years. There were 8 TITA Qs this year. Overall this section was at a medium level of difficulty.
Question 3 If \((a+b \sqrt{3})^2=52+30 \sqrt{3}\), where \(a\) and \(b\) are natural numbers, then \(a+b\) equals
\[
\begin{array}{l}
(a+b \sqrt{3})^2=52+30 \sqrt{3} \\
a^2+3 b^2+2 a b \sqrt{3}=52+30 \sqrt{3}
\end{array}
\]
Comparing the terms, we get:
\[
\begin{array}{l}
a^2+3 b^2=52 \\
a b=15
\end{array}
\]
So, \((a, b)=(1,15),(15,1),(3,5)\) and \((5,3)\)
The only possibility for the above system of equations is, \(a=5, b=3\)
Hence, \(a+b=5+3=8\)
The question is "If \((a+b \sqrt{3})^2=52+30 \sqrt{3}\), where \(a\) and \(b\) are natural numbers, then \(a+b\) equals"
Choice C is the correct answer.
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