Question

Question 1 (ii)
Find the sum of the following APs
(ii) − 37, − 33, − 29 ,…, to 12 terms

Answer 1

(ii) $-37,-33,-29,\dots \dots ,to12termsForthisA.P.,a=-37d=a_2-a_1=(-33)-(-37)=-33+37=4n=12Weknowthat,S_n=\frac{n}{2}[2a+(n-1\left)d\right]S_{12}=\frac{12}{2}\left[2\right(-37)+(12-1)\times 4]=6[-74+11\times 4]=6[-74+44]=6(-30)=-180$