Question

In the arithmetic sequence {13, 6,-1,-8,...}, what is the common difference?

Answer 1

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Answer = -7

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Known

a = 13

U2 = 6

U3 = -1

U4 = -8

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Question

d = ..?

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Way to do

#since it gives a lot of number, i will just pick one of the nth term, ill choose U2

Un = a + (n-1)d

U2 = 13 + (2-1)d

6 = 13 + d

6 - 13 = d

d = -7

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Note

• The formula of arithmetic sequence

Un = a + (n-1)d

n = nth term

a = first term

d = common difference

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