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The greatest number among 2тАЛ, 31/3, 41/4 is:
All are equal
41/4
31/3
2тАЛ
31/3
Find the Least Common Multiple (LCM) of the denominators of the fractional exponents (2, 3, and 4), which is 12. Raise each number to the power of 12 and compare the resulting integers.
Three numbers to compare: 2тАЛ, 31/3, and 41/4.
a1/n=naтАЛ
Find the Least Common Multiple (LCM) of the denominators of the fractional exponents (2, 3, and 4), which is 12. Raise each number to the power of 12 and compare the resulting integers.
Students often wrongly assume the base with the largest number (4) is the largest overall, ignoring the effect of the fractional exponent.
Convert radicals to fractional exponents
Rewrite 2тАЛ as 21/2, 31/3 remains as is, and 41/4 can be simplified if desired, but we will proceed with the original values.
21/2,31/3,41/4
Find the LCM of denominators
The denominators are 2, 3, and 4. Their LCM is 12.
LCM(2,3,4)=12
Raise each term to the power of 12
Calculate (21/2)12=26=64, (31/3)12=34=81, and (41/4)12=43=64.
26=64,34=81,43=64
Compare results
Comparing the values 64, 81, and 64, clearly 81 is the greatest.
81>64
C is correct because 31/3 corresponds to the largest value (81) among the calculated powers.
This method of raising to the LCM of roots is the standard approach for comparing radicals and surds in competitive exams.