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10 questions from this quiz
Constant difference between terms
Tn=a+(n−1)dT_n = a + (n - 1)dTn=a+(n−1)d
A straight line
Second differences are constant
r=TnTn−1r = \frac{T_n}{T_{n-1}}r=Tn−1Tn
Tn=arn−1T_n = ar^{n-1}Tn=arn−1
The index variable
Sn=n2[a+l]S_n = \frac{n}{2}[a + l]Sn=2n[a+l]
Sn=a(rn−1)r−1S_n = \frac{a(r^n - 1)}{r - 1}Sn=r−1a(rn−1)
−1<r<1-1 < r < 1−1<r<1
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