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If $a = 2^3 \cdot 3^4 \cdot 5^2$ and $b = 2^4 \cdot 3^2 \cdot 7$, then $\dfrac{\text{LCM}(a,b)}{\text{HCF}(a,b)}$ equals
A$2^7 \cdot 3^6 \cdot 5^2 \cdot 7$
B$2 \cdot 3^2 \cdot 5 \cdot 7$
C$2 \cdot 3^2 \cdot 5^2 \cdot 7$
D$2^4 \cdot 3^4 \cdot 5^2 \cdot 7$
Answer & Solution
Correct answer: C. $2 \cdot 3^2 \cdot 5^2 \cdot 7$
HCF takes min powers: $2^3 3^2$. LCM takes max powers: $2^4 3^4 5^2 7$. Ratio $= 2^{4-3} 3^{4-2} 5^2 7 = 2\cdot3^2\cdot5^2\cdot7$.
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