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The smallest integer nn for which 4n>17194^n > 17^{19} holds, is closest to

Solution

✅ Correct Option: 1

We need to find the smallest integer nn such that 4n>17194^n > 17^{19}.

Comparing these huge numbers directly is impossible! We need a smarter approach.


When we have equations or inequalities with different bases and exponents, logarithms are our best friend. They convert multiplication into addition and powers into multiplication.

If a>ba > b (where a,b>0a, b > 0), then log⁡(a)>log⁡(b)\log(a) > \log(b).


Starting with: 4n>17194^n > 17^{19}

Take the natural logarithm of both sides:

ln⁡(4n)>ln⁡(1719)\ln(4^n) > \ln(17^{19})

Use the logarithm property ln⁡(ab)=bln⁡(a)\ln(a^b) = b \ln(a):

nln⁡(4)>19ln⁡(17)n \ln(4) > 19 \ln(17)

Solve for nn:

n>19ln⁡(17)ln⁡(4)n > \dfrac{19 \ln(17)}{\ln(4)}


We need to find ln⁡(4)\ln(4) and ln⁡(17)\ln(17):

For ln⁡(4)\ln(4): Since 4=224 = 2^2, we have ln⁡(4)=ln⁡(22)=2ln⁡(2)≈2×0.693=1.386\ln(4) = \ln(2^2) = 2\ln(2) \approx 2 \times 0.693 = 1.386

For ln⁡(17)\ln(17): ln⁡(17)≈2.833\ln(17) \approx 2.833

Substituting:

n>19×2.8331.386=53.8271.386≈38.84n > \dfrac{19 \times 2.833}{1.386} = \dfrac{53.827}{1.386} \approx 38.84


Since we need the smallest integer nn such that 4n>17194^n > 17^{19}, and we found n>38.84n > 38.84, the answer is:

n=39n = 39

For n=38n = 38: 4384^{38} would be slightly smaller than 171917^{19}

For n=39n = 39: 4394^{39} is the first power of 4 that exceeds 171917^{19}

When comparing exponential expressions with different bases, logarithms transform the problem into simple arithmetic!

Therefore, the smallest integer nn is 39.

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