Let f ( x ) be a function with two properties:
(a) For any two real numbers x and y , f ( x + y ) = x + f ( y ) and
(b) f ( 0 ) = 2
If α is a Real Number and both β and γ are positive integers
arcsin ( f ( 1 0 0 ) ) = α − i ln ( β + γ )
Evaluate ⌊ α β γ ⌋ .
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I would like to add to Azhaghu Roopesh M solution, on how to find the value of ζ . It follows as :
Setting y = 0 in the functional equation, we get
f ( x ) = x + f ( 0 ) = x + 2
And thus,
ζ = f ( 1 0 0 ) = 1 0 0 + 2 = 1 0 2 .
The rest of the work has already been done by my dear friend.
I've cleaned the question up a bit. Nice problem.
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Yeah, looks good now . Thanks Jake ⌣ ¨
Many many thanks to @Kishlaya Jaiswal for introducing me to finding complex solutions of Inverse Trigonometric Ratios .
@Calvin Lin I wanted to make this question a community post for this wiki by Kishlaya , but I couldn't do so . Can you please help me out ?
Thanks sir !!
If anyone wants to know how I began with the proof , please visit this Brilliant wiki by Kishlaya Jaiswal .
Okay, so let's begin by defining f ( x ) . Set y = 0 ; this gives f ( x ) = x + f ( 0 ) = x + 2 .
This gives us ζ = f ( 1 0 0 ) = 1 0 0 + 2 = 1 0 2 . We want to find s i n − 1 ( 1 0 2 )
Now comes the tricky part. I assume that the reader is familiar with Euler's formula, which is e i θ = c o s ( θ ) + i s i n ( θ ) ; from it we can derive the following:
s i n ( θ ) = 2 e i θ − e − i θ
Let e i ∗ θ = y . We have: y − y 1 = 2 0 4 i ; solving for y yields:
y = 2 2 0 4 i ± − 4 1 6 1 6 + 4 = 2 2 0 4 i ± 2 i 1 0 4 0 3
y = 1 0 2 i ± i 1 0 4 0 3
Thus, i θ = l n ( y ) = l n ( i ) + l n ( 1 0 2 ± 1 0 4 0 3 ) . I assume that the final answer you seek is the principal value of the expression; in other words, l n ( i ) = 2 i π .
Therefore, θ = 2 π − i ∗ l n ( 1 0 2 + 1 0 4 0 3 ) ; the product ω equals 2 1 0 2 ∗ 1 0 4 0 3 ∗ π ≈ 1 6 6 6 7 8 1 . 4 ; thus, the greatest integer smaller than ω is 1 6 6 6 7 8 1 .
same method by me too
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The solution for the first part of the question has been provided by my friend Kish below
The value of ζ = f ( 1 0 0 ) evaluates to be 1 0 2 .
We all know that arcsin ( n ) = − i ⋅ l n ( i ⋅ n ± 1 − n 2 ) = − i ⋅ l n ( i ⋅ n ± i m = − i ⋅ l n ( i ( n ± m ) )
Now we use e i x = c o s ( x ) + i ⋅ s i n ( x ) and = l n ( i ⋅ x ) = l n ( x ⋅ e i ⋅ 2 π ) = − i ⋅ ( l n ( x ) + i ⋅ 2 π ) = 2 π − l n ( x )
So we get → 2 π − i ⋅ l n ( n ± m )
So we have arcsin ( 1 0 2 ) = 2 π − i ⋅ l n ( 1 0 2 + 1 0 1 ⋅ 1 0 3 ) .
Therefore the product evaluates to 1 6 6 6 7 8 1 . 4 0 7 and hence the final answer is 1 6 6 6 7 8 1 .