+180 An arithmetic series –56 – 44 – 32 – 20 – ... +tₙ has a sum of 988. Determine the number of terms in the series.
+9673 First term = -56
Common difference = (-44) - (-56) = 12
Let n be the number of terms. Using the formula for arithmetic series,
\(\dfrac n2 (2(-56) + (n - 1)(12)) = 988\)
This is now a quadratic equation in n. Can you take it from here? Just note that n is a positive integer.
