Question

Question 6 Write the first five terms of the sequences whose nth term is an = n(n^2 + 5)/4

Class X1 - Maths -Sequences and Series Page 180

Answer 1

$a_n=\frac{n(n^2+5)}{4}\\\\\\1st-term(a_1)=\frac{1.(1^2+5)}{4}\\a_1=\frac{6}{4}\\\\a_1=\frac{3}{2}\\\\\\2nd-term(a_2)=\frac{2(2^2+5)}{4}\\\\a_2=\frac{9}{2}\\\\3rd-term(a_3)=\frac{3(3^2+5)}{4}\\\\a_3=\frac{21}{2}\\\\4th-term(a_4)=\frac{4(4^2+5)}{4}\\\\a_4=\frac{21}{1}\\\\5th-term(a_5)=\frac{5(5^2+5)}{4}\\\\a_5=\frac{75}{2}$