Evaluate: ab – bc if a = 4, b = 3, and c = 2 ab - bc =
2 answers:
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Answer:
B. 1635
Step-by-step explanation:
We have been given that the seating for an outdoor stage is arranged such that there are 11 seats in the first row. For each additional row after the first row, there are 3 more seats than there are in the previous row.
We can see that the seating order is in form of arithmetic sequence, whose first term is 11 and common difference is 3.
Since there are 30 rows altogether, so we need to find the sum of 30 first terms of the sequence using sum formula.
, where,
Sum of n terms,
n = Number of terms,
a = First term,
d = Common difference.
Upon substituting our given value is above formula, we will get:
Therefore, there are 1635 seats in all and option B is the correct choice.