Question

the first term of anAP is _5 and the last term is 45.if the sum of the term is 120.then find number of terms​

Answer 1

Answer:

hope it may help you

n=24

Answer 2

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1st Term = 5 = a

Last Term = 45 = L

Sum of all the Terms = 120 = Sⁿ

So, we know

$Sⁿ = \frac{n}{2} + [ a + l ] \\ \\ put \: \: the \: \: values \: \: = > \\ \\ 120 = \frac{n}{2} \: [ 5 + 45] \\ \\ 120 = \frac{n}{2} \: \times 50 \\ \\ 120 = 25n \\ \\ \frac{120}{25} = n \\ \\ \frac{24}{5} = n \\ \\ \\ {\large{\boxed{24 = n}}}$

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