MATHEMATICS

JAMB 2012 - Question 19

Mathematics 2012 JAMB Past Questions - Question 19: the nth term of a sequence is n² - 6n – 4 find the sum of the 3rd and 4th terms

the nth term of a sequence is n² - 6n – 4 find the sum of the 3rd and 4th terms
A:
B:
C:
D:
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Correct Answer

D

Explanation

nth = n² - 6n – 43rd term = 3² 6(3) – 4 9 – 18 – 4 = - 134th term = 4² - 6(4) - 4 16 - 24 – 4 = - 12 Sum = - 13 + (-12) = - 25 To find the sum of the 3rd and 4th terms of the sequence, we need to substitute the values of n = 3 and n = 4 into the given expression for the nth term.For the 3rd term (n = 3):T₃ = (3)² - 6(3) - 4T₃ = 9 - 18 - 4T₃ = -13For the 4th term (n = 4):T₄ = (4)² - 6(4) - 4T₄ = 16 - 24 - 4T₄ = -12Now, let's find the sum of the 3rd and 4th terms:Sum = T₃ + T₄Sum = -13 + (-12)Sum = -25Therefore, the sum of the 3rd and 4th terms of the sequence is -25.