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Each term of a sequence is the sum of it...

Each term of a sequence is the sum of its preceding two terms from the third term onwards. The second term of the sequence is -1 and the 10th term is 29. The first term is `"_________"`

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To find the first term of the sequence, we will denote the terms of the sequence as \( a_1, a_2, a_3, \ldots \) and apply the information given in the problem. ### Step-by-Step Solution: 1. **Understanding the Sequence**: The sequence is defined such that each term from the third term onward is the sum of the two preceding terms. This can be expressed as: \[ a_{k+2} = a_k + a_{k+1} \] for \( k \geq 1 \). 2. **Given Values**: We are given: - \( a_2 = -1 \) - \( a_{10} = 29 \) 3. **Expressing Terms**: We can express the terms in terms of \( a_1 \): - For \( a_3 \): \[ a_3 = a_1 + a_2 = a_1 - 1 \] - For \( a_4 \): \[ a_4 = a_2 + a_3 = -1 + (a_1 - 1) = a_1 - 2 \] - For \( a_5 \): \[ a_5 = a_3 + a_4 = (a_1 - 1) + (a_1 - 2) = 2a_1 - 3 \] - For \( a_6 \): \[ a_6 = a_4 + a_5 = (a_1 - 2) + (2a_1 - 3) = 3a_1 - 5 \] - For \( a_7 \): \[ a_7 = a_5 + a_6 = (2a_1 - 3) + (3a_1 - 5) = 5a_1 - 8 \] - For \( a_8 \): \[ a_8 = a_6 + a_7 = (3a_1 - 5) + (5a_1 - 8) = 8a_1 - 13 \] - For \( a_9 \): \[ a_9 = a_7 + a_8 = (5a_1 - 8) + (8a_1 - 13) = 13a_1 - 21 \] - For \( a_{10} \): \[ a_{10} = a_8 + a_9 = (8a_1 - 13) + (13a_1 - 21) = 21a_1 - 34 \] 4. **Setting Up the Equation**: We know that \( a_{10} = 29 \), so we can set up the equation: \[ 21a_1 - 34 = 29 \] 5. **Solving for \( a_1 \)**: Rearranging the equation gives: \[ 21a_1 = 29 + 34 \] \[ 21a_1 = 63 \] \[ a_1 = \frac{63}{21} = 3 \] ### Conclusion: The first term \( a_1 \) is \( 3 \).
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RESONANCE ENGLISH-SEQUENCE & SERIES -EXERCISE -1 PART -I RMO
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