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Determine the number of terms in the A....

Determine the number of terms in the A.P. 3,4,5, …, 399 . Also find its ` 25^(th)` term .

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Given A.P. is
3, 4, 5, … 399
Let n be the number of terms
then ` 399 = a + (n-1) d = 3 + (n-1) xx1`
` rArr 396 = n-1`
` rArr n= 397 `
` therefore ` Number of terms = 397
Also , ` a_(25) = a + 24d `
` = 3 + 34 xx1 `
= 27 `
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