Let f(x)=2x+2+1622x+1+2x+4+32f(x) = \frac{2^{x+2} + 16}{2^{2x+1} + 2^{x+4} + 32}. Then the value of 8(f(115)+f(215)+…+f(5915))8\left(f\left(\frac{1}{15}\right) + f\left(\frac{2}{15}\right) + \ldots + f\left(\frac{59}{15}\right)\right) is equal to

Answer: 118

Step-by-step solution

Step 1: Simplify the function f(x)f(x)

First, we simplify the given function f(x)f(x). We can rewrite the terms in the numerator and denominator using the exponent rule am+n=am⋅ana^{m+n} = a^m \cdot a^n. This allows us to express all terms in terms of 2x2^x.

Step 2: Factor out common terms

Next, we factor out common terms from the numerator and denominator. In the numerator, we factor out 4. In the denominator, we factor out 2 and recognize that the remaining quadratic expression is a perfect square trinomial, (2x+4)2(2^x + 4)^2.

Step 3: Further simplify f(x)f(x)

We can cancel out one factor of (2x+4)(2^x + 4) from the numerator and denominator, simplifying the function to f(x)=22x+4f(x) = \frac{2}{2^x + 4}. This is the most simplified form of the function.

Step 4: Find the relationship between f(x)f(x) and f(4−x)f(4-x)

Now, let's evaluate f(4−x)f(4-x) to see if there's a useful relationship. We substitute (4−x)(4-x) into the simplified function. After algebraic manipulation, we find that f(x)+f(4−x)=22x+4+2x8+2⋅2x=22x+4+2x2(4+2x)=4+2x2(2x+4)=12f(x) + f(4-x) = \frac{2}{2^x + 4} + \frac{2^x}{8 + 2 \cdot 2^x} = \frac{2}{2^x + 4} + \frac{2^x}{2(4 + 2^x)} = \frac{4 + 2^x}{2(2^x + 4)} = \frac{1}{2}.

Step 5: Pair the terms in the sum

The sum is S=f(115)+f(215)+…+f(5915)S = f\left(\frac{1}{15}\right) + f\left(\frac{2}{15}\right) + \ldots + f\left(\frac{59}{15}\right). We notice that the terms can be paired such that the sum of the arguments is 4. For example, 115+5915=6015=4\frac{1}{15} + \frac{59}{15} = \frac{60}{15} = 4. There are 29 such pairs, and one middle term f(3015)=f(2)f\left(\frac{30}{15}\right) = f(2).

Step 6: Calculate the sum

Each pair sums to 12\frac{1}{2}. There are 29 such pairs. The middle term is f(2)=222+4=24+4=28=14f(2) = \frac{2}{2^2 + 4} = \frac{2}{4+4} = \frac{2}{8} = \frac{1}{4}. So the total sum is 29⋅12+14=584+14=59429 \cdot \frac{1}{2} + \frac{1}{4} = \frac{58}{4} + \frac{1}{4} = \frac{59}{4}.

Step 7: Calculate the final value

Finally, we need to multiply the sum SS by 8 to get the required value.

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