Question

Find 7th term of the AP whose nth term is given by an=(-1)n-1.ncube

Answer 1

$an \: = ( - 1)n - 1.n {}^{3}$

$a7 = ( - 1)7 - 1.7 {}^{3}$

$a7 = - 7 - 343$

$a7 = - 350$