Problem Analysis #18

48.83s
9,405 toks
Problem Statement

Let R\mathbb{R} denote the set of all real numbers. Let f:RRf: \mathbb{R} \to \mathbb{R} be a function such that f(x)>0f(x) > 0 for all xRx \in \mathbb{R}, and f(x+y)=f(x)f(y)f(x + y) = f(x)f(y) for all x,yRx, y \in \mathbb{R}.Let the real numbers a1,a2,,a50a_1, a_2, \ldots, a_{50} be in an arithmetic progression. If f(a31)=64f(a25)f(a_{31}) = 64f(a_{25}), andi=150f(ai)=3(225+1),\sum_{i=1}^{50} f(a_i) = 3(2^{25} + 1),find the value ofi=630f(ai).\sum_{i=6}^{30} f(a_i).\

Ground Truth
96
Execution Trace
Reasoning Process

[THOUGHT] The function ( f ) satisfies ( f(x + y) = f(x)f(y) ) and ( f(x) > 0 ), implying ( f(x) = b^x ) for some ( b > 0 ). Given ( f(a_{31}) = 64f(a_{25}) ), we find ( b^{6d} = 64 ), leading to ( b = 2^{1/d} ). Thus, ( f(x) = 2^{x/d} ).

The arithmetic progression terms are ( a_i = a + (i-1)d ). Therefore, ( f(a_i) = 2^{(a + (i-1)d)/d} = 2^{a/d + i - 1} = 2^k \cdot 2^{i-1} ) where ( k = a/d ).

The total sum ( \sum_{i=1}^{50} f(a_i) = 2^k (2^{50} - 1) = 3(2^{25} + 1) ). Solving for ( 2^k ): [ 2^k = \frac{3(2^{25} + 1)}{2^{50} - 1} = \frac{3}{2^{25} - 1} ]

The sum from ( i=6 ) to ( 30 ) is a geometric series with 25 terms starting from ( i=6 ): [ \sum_{i=6}^{30} f(a_i) = 2^{k+5} \sum_{j=0}^{24} 2^j = 2^{k+5} (2^{25} - 1) ] Substituting ( 2^k = \frac{3}{2^{25} - 1} ): [ 2^{k+5} (2^{25} - 1) = 32 \cdot \frac{3}{2^{25} - 1} \cdot (2^{25} - 1) = 96 ]

[PYTHON]

Verification of the key steps

Given the derived formula for the sum from i=6 to 30

k = 3 / (225 - 1) sum_6_to_30 = 32 * k * (225 - 1) print(int(sum_6_to_30)) [/PYTHON]

[THOUGHT] The Python code confirms the sum from ( i=6 ) to ( 30 ) is 96. Thus, the final answer is (\boxed{96}). </think>

[THOUGHT] The function ( f ) satisfies ( f(x + y) = f(x)f(y) ) and ( f(x) > 0 ), implying ( f(x) = b^x ) for some ( b > 0 ). Given ( f(a_{31}) = 64f(a_{25}) ), we find ( b^{6d} = 64 ), leading to ( b = 2^{1/d} ). Thus, ( f(x) = 2^{x/d} ).

The arithmetic progression terms are ( a_i = a + (i-1)d ). Therefore, ( f(a_i) = 2^{(a + (i-1)d)/d} = 2^{a/d + i - 1} = 2^k \cdot 2^{i-1} ) where ( k = a/d ).

The total sum ( \sum_{i=1}^{50} f(a_i) = 2^k (2^{50} - 1) = 3(2^{25} + 1) ). Solving for ( 2^k ): [ 2^k = \frac{3(2^{25} + 1)}{2^{50} - 1} = \frac{3}{2^{25} - 1} ]

The sum from ( i=6 ) to ( 30 ) is a geometric series with 25 terms starting from ( i=6 ): [ \sum_{i=6}^{30} f(a_i) = 2^{k+5} \sum_{j=0}^{24} 2^j = 2^{k+5} (2^{25} - 1) ] Substituting ( 2^k = \frac{3}{2^{25} - 1} ): [ 2^{k+5} (2^{25} - 1) = 32 \cdot \frac{3}{2^{25} - 1} \cdot (2^{25} - 1) = 96 ]

[PYTHON]

Verification of the key steps

Given the derived formula for the sum from i=6 to 30

k = 3 / (225 - 1) sum_6_to_30 = 32 * k * (225 - 1) print(int(sum_6_to_30)) [/PYTHON]

[THOUGHT] The Python code confirms the sum from ( i=6 ) to ( 30 ) is 96. Thus, the final answer is (\boxed{96}). </think>

\boxed{96}

Tool Output
[PYTHON OUTPUT] 96 [/PYTHON OUTPUT] [PYTHON OUTPUT] 96 [/PYTHON OUTPUT]
Reasoning Process

[THOUGHT] The Python output confirms the sum from ( i=6 ) to ( 30 ) is 96. Thus, the final answer is (\boxed{96}). [/THOUGHT]

Final Model Output
96

Comparative Analysis (P18) (Average across runs)

Avg Time Taken

Llama-VARCO-8B-Instruct
103.6
Gemini-3-Pro-Preview
52.0
Solar-Pro-2 (31B)(high)
48.8
Deepseek-V3.2
38.6
HCX-007(high)
32.0
A.X-4.0 (72B)
31.1
Grok-4.1-fast
27.7
Claude-Opus-4.5
22.0
GPT-5.1 (high)
17.3
EXAONE-4.0.1-32B (high)
5.7

Avg Token Usage

Solar-Pro-2 (31B)(high)
9405.0
Grok-4.1-fast
7425.0
Gemini-3-Pro-Preview
6113.0
Deepseek-V3.2
5286.0
Claude-Opus-4.5
5158.0
HCX-007(high)
4565.0
EXAONE-4.0.1-32B (high)
4213.0
Llama-VARCO-8B-Instruct
3600.0
GPT-5.1 (high)
3114.0
A.X-4.0 (72B)
2654.0