Question 1 (ii) Find the sum of the following APs
(ii) − 37, − 33, − 29 ,…, to 12 terms
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Solution
(ii) −37,−33,−29,……,to12termsForthisA.P.,a=−37d=a2−a1=(−33)−(−37)=−33+37=4n=12Weknowthat,Sn=n2[2a+(n−1)d]S12=122[2(−37)+(12−1)×4]=6[−74+11×4]=6[−74+44]=6(−30)=−180