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If the first term of an AP is -5 and the...

If the first term of an AP is -5 and the common difference is 2, then the sum of the first 6 terms is

A

0

B

5

C

6

D

15

Text Solution

Verified by Experts

The correct Answer is:
A
Given, `a= -5` and `d=2`
` :. S_(6)=(6)/(2)[2a+(6-1)d] " " [ :' S_(n)=(n)/(2){2a+(n-1)d}]`
` " " =3[2(-5)+5(2)] " " =3(-10+10)=0`
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NCERT EXEMPLAR-ARITHMETIC PROGRESSIONS-Arithmetic Progressions
  1. The 4th term from the end of an AP -11, -8, -5, …, 49 is

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  2. The famous mathematician associated with finding the sum of the first ...

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  3. If the first term of an AP is -5 and the common difference is 2, then ...

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  4. The sum of first 16 terms of the AP 10, 6, 2, … is

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  5. In an AP, if a = 1, a(n)= 20 and S(n) = 399, then n is equal to

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  6. The sum of first five multiples of 3 is

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  7. Which of the following form of an AP ? Justify Your answer. (i) -1,-...

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  8. Justify whether it is true to say that -1, (-3)/(2), -2, (5)/(2), … ...

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  9. For the AP -3, -7, -11, … can we find directly a(30)-a(20) without ac...

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  10. Two A.P have the same common difference. The first term of one A.P is ...

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  11. Is 0 a term of the AP 31, 28, 25, …? Justify your answer.

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  12. The taxi fare after each km, when the fare is Rs. 15 for the first km ...

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  13. In which of the following situations, do the lists of numbers involved...

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  14. Justify whether it is true to say that the following are the nth terms...

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  15. Match the AP's given in column A with suitable common differences giv...

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  16. Verify that each of the following is an AP and then write its next thr...

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  17. Write the first three terms of the AP's, when a and d are as given bel...

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  18. Find a, b and c such that the following numbers are in AP, a, 7, b, 23...

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  19. Determine the AP whose fifth term is 19 and the difference of the eigh...

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  20. The 26th, 11th and the last terms of an AP are, 0, 3 and -(1)/(5), res...

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