CAT 2025 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 9 : If \( 12 ^ { 12 x } \times 4 ^ { 24 x + 12 } \times 5 ^ { 2 y } = 8 ^ { 4 z } \times 20 ^ { 12 x } \times 243 ^ { 3 x - 6 } \), where \( x , y \) and \( z \) are natural numbers, then \( x + y + z \) equals
Given:
\[
12^{12x}\times4^{24x+12}\times5^{2y}
=8^{4z}\times20^{12x}\times243^{3x-6}
\]
Express all numbers in prime factors.
Left-Hand Side:
\[
12^{12x}=2^{24x}\times3^{12x}
\]
\[
4^{24x+12}=2^{48x+24}
\]
Therefore:
\[
LHS=2^{72x+24}\times3^{12x}\times5^{2y}
\]
Right-Hand Side:
\[
8^{4z}=2^{12z}
\]
\[
20^{12x}=2^{24x}\times5^{12x}
\]
\[
243^{3x-6}=3^{15x-30}
\]
Therefore:
\[
RHS=2^{12z+24x}\times3^{15x-30}\times5^{12x}
\]
Equating powers of 3:
\[
12x=15x-30\Rightarrow x=10
\]
Equating powers of 5:
\[
2y=12x\Rightarrow y=6x=60
\]
Equating powers of 2:
\[
72x+24=12z+24x
\]
\[
48x+24=12z
\]
\[
z=4x+2=42
\]
Therefore:
\[
x+y+z=10+60+42=112
\]
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