I found the solution to the problem complicated in the 5lb books. Particularly, the part after finding the last term. Is there any other explanation other than the 5lb?
Thanks!
Use formula Sn = n/2[2a + (n-1)d]
where n = no. of terms
a=first term ’ d = difference In this case, n =100, a=45, d=2
S100 = 100/2(2*45 + (100-1)2) = 50(90+198)=50288 = 14400
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