(o) A certain sequence has a constant second diffierence of 8. The sixth term of the sequence is 172 and the tenth term is 452. Determine the general term.
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To find the general term of the sequence with a constant second difference of 8, we can express it as a quadratic equation. The general form of such a sequence can be given as \( a_n = An^2 + Bn + C \), where \( A \), \( B \), and \( C \) are constants to be determined. Since the second difference is constant and equal to 8, we know that \( 2A = 8 \), leading us to \( A = 4 \). Now we substitute the known terms into our equation: 1. For \( n = 6 \), \( a_6 = 172 \): \[ 4(6^2) + B(6) + C = 172 \] \[ 144 + 6B + C = 172 \] \[ 6B + C = 28 \] (Equation 1) 2. For \( n = 10 \), \( a_{10} = 452 \): \[ 4(10^2) + B(10) + C = 452 \] \[ 400 + 10B + C = 452 \] \[ 10B + C = 52 \] (Equation 2) Now we have a system of equations: - From Equation 1: \( 6B + C = 28 \) - From Equation 2: \( 10B + C = 52 \) Subtract these equations to eliminate \( C \): \[ (10B + C) - (6B + C) = 52 - 28 \] \[ 4B = 24 \implies B = 6 \] Now, substituting \( B = 6 \) back into Equation 1: \[ 6(6) + C = 28 \implies 36 + C = 28 \implies C = -8 \] Thus, we have found \( A \), \( B \), and \( C \): - \( A = 4 \) - \( B = 6 \) - \( C = -8 \) The general term of the sequence is given by: \[ a_n = 4n^2 + 6n - 8 \] And there you have the general term!