Question

which term of the arithmetic progression 24, 21, 18.......... is the first negative term

Answer 1

a=24
d=-3
[tex] a_{n} \ \textless \ 0 \\ a+(n-1)d \ \textless \ 0 \\ 24+(n-1)(-3) \ \textless \ 0 \\ 24-3n+3\ \textless \ 0 \\ 3(9-n)\ \textless \ 0 \\ 9-n\ \textless \ 0 \\ 9\ \textless \ n \\ \\ so... n=10[/tex]