Q3 of 89 Page 49

For the AP - 3, - 7, - 11, … can we find directly a30 - a20 without actually finding a30 and a20 reason for your answer.

True

Given


First term, a = - 3


Common difference, d = a2 - a1 = - 7 - (- 3) = - 4


a30 - a20 = a + 29d - (a + 19d)


= 10d


= - 40


It is so because difference between any two terms of an AP is proportional to common difference of that AP


More from this chapter

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1

Which of the following form of an AP? Justify your answer.

 2

Justify whether it is true to say that forms an AP as a2 - a1 = a3 - a2

 4

Two AP’s have the same common difference. The first term of one AP is 2 and that of the other is 7. The difference between their 10th terms is the same as the difference between 21st terms, which is the same as the difference between any two corresponding terms? why?

 5

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