Question

If an AP the first term is 3 and the last term is 20 the sum of all term is 460 what is the value of n?

Answer 1

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Answer 2

Answer:

Step-by-step explanation:

⇆a=3

⇔l=20

⇔$s_{n} =a+(n-1)d=460$

⇔$s_{n} =n/2(2a+n-1)d$

⇔$s_{n} =n/2(6+(n-1)d)=460$

⇔$s_{n} =n/2(6+20)$

⇔$s_{n} =n/2(26)$

⇔$s_{n} =13n$

⇔$13n=460\\n=35.2$