Hello, Can you help me with the following question:My family is planning to build a brick wall that approximates the shape of a trapezoid. The shorter base of the trapezoid needs to start with a row of 5 bricks, and each row must increase by 2 bricks on each side until there are 20 rows. How can I go about finding out how many bricks I will need to buy so that I don’t spend more money than needed?

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VelindaW420226 VelindaW420226 · Answer 1 · 2022-10-28T05:00:02+02:00

In this problem, we have the sequence

5,9,13,17,21,...

Is an arithmetic sequence

the common difference is d=4

there are 20 terms (rows) in the sequence

Remember that

The rule to find the sum of the first n terms of the arithmetic sequence is equal to

[tex]S=\frac{n}{2} [2a_1+(n-1)d][/tex]

where

n=20

a1=5 ----> first term

d=4

substitute given values

[tex]S=\frac{20}{2}[2(5)+(20-1)4][/tex]

S=860

therefore