Question 9 Find the 9th term in the following sequence whose nth term is an = (-1)^(n-1) n^3; a9
Class X1 - Maths -Sequences and Series Page 180
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Answered by
6
An = (-1)^(n-1).n³
for finding 9th term put 9 in place of n , and then calculate .
A₉ = (-1)⁽⁹⁻¹⁾.9³
= (-1)⁸.729
= 1 × 729
= 729
for finding 9th term put 9 in place of n , and then calculate .
A₉ = (-1)⁽⁹⁻¹⁾.9³
= (-1)⁸.729
= 1 × 729
= 729
Answered by
2
729
Given:
an = (-1)^(n-1) n^3
To Find:
a9 of the sequence
Calculating:
an = (-1)^(n-1) n^3
Putting the value of n in this equation as 9:
a9 = (-1)^(9-1)(9)^3
a9 = (-1)^(8) (9)^3
a9 = 1 x (9)^3
(When negative 1 is raised to an even number then the 1 becomes positive if it is raised to an odd number then the one remains negative)
a9 = (9)^3
a9 = 729
Therefore, the 9th term of the Sequence is 729.
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