Join 60,000+ competitive exam aspirants
If 2K×412=1611, then the value of K is:
20
16
10
24
20
Express all terms with base 2: 4=22 and 16=24. The equation becomes 2K×(22)12=(24)11, which simplifies to K+24=44.
The equation given is 2K×412=1611.
(am)n=am×n,am×an=am+n
Express all terms with base 2: 4=22 and 16=24. The equation becomes 2K×(22)12=(24)11, which simplifies to K+24=44.
Students often make mistakes by multiplying the bases or failing to convert 4 and 16 into powers of 2 before equating the exponents.
Express all bases as powers of 2
Since the base of the first term is 2, express 4 as 22 and 16 as 24.
4=22,16=24
Substitute and simplify powers
Substitute these into the equation and use the power of a power rule (am)n=amn.
2K×(22)12=(24)11⟹2K×224=244
Apply product rule and equate exponents
Use am×an=am+n to simplify the left side, then equate the exponents of base 2.
2K+24=244⟹K+24=44
Solve for K
Subtract 24 from both sides to isolate K.
K=44−24=20
A is correct because the calculation leads to K = 20.
This exponent rule is fundamental for logarithmic equations and solving complex base-conversion problems in competitive exams.