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Friday, April 29, 2016

Compare the numbers X=(log2(5+1))3 and Y=1+log2(5+2).

Compare the numbers X=(log2(5+1))3 and Y=1+log2(5+2).

First, note that 5>1, which gives 25>2 and further translates into 5+25+1=(5+1)2>8, which implies 5+1>232, taking base 2 logarithm of both sides of the inequality we get:

log2(5+1)>32

(log2(5+1))3>(32)3=278

On the other hand, we have

52>5

92=52+2>5+2

log2(92)>log2(5+2)

log291>log2(5+2)

1+log291>1+log2(5+2)

log29>1+log2(5+2)

If we can prove 278>log29, then we can say X>Y.

Note that 227=(25)5+2>4(33)5>316=98, this suggest 278>log29 and we're hence done as we can conclude X>Y.

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