Math, asked by rutujakesari, 7 months ago

an A.P.1st term is 1 and the last term is 149.The sum of all terms is 5625 then number of term is... *
1 point
150
149
74
75​

Answers

Answered by zaidvadtalwala
2

Answer:

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First term of AP, a = 5

Let no of terms be 'n' and common difference is 'd'

Last term of AP, an = 45

Given, sum of n terms = 400

And we know, sum of an AP if first term(a) and last term(an) is given,

Putting the values, we get,

⇒ 800 = 50n

⇒ n = 16

i.e. 16 terms are there and 16th term is last and equal to 45

Also, we know,

nth term of an AP,

Where, a and d are first term and common difference, respectively.

As, a16 = 45

⇒ a + 15d = 45

⇒ 5 + 15d = 45

⇒ 15d = 40

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