Question

Value of a11 and s11

Answer 1

Answer and Step-by-step explanation:

The formula for an arithmetic sequence is:

`a_(n) = a_(1) + (n-1)d`

Plug in the given values.

`a_(11) = 2.5 + (11 -1)(1.5)\\\\a_(11)=2.5 + (10)(1.5)\\\\a_(11) = 2.5 + 15\\\\a_(11)=4`

The formula for the sum on an arithmetic sequence is:

`S_(n) = (n(a_1+a_n))/(2)`

Plug in the values.

`S_(11) = (11(2.5 + 4))/(2) = 35.75`

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I hope this helps!