Nth Term of AP
Nth Term of an AP
The nth term of an AP is
Illustration 1. Find the fifteenth term of the AP - 3, - 9, - 15, ...
A - 87 B -84 C. -88 D. -90
Answer: A
Solution: in the given series -3, -9,-15
The difference between second and first term is
-9 -(-3) = -9 + 3 = -6
The difference between third and second term is
-15 -(-9) = -15 + 9 = -6
Thus here
a = -3, d = -9 - (-3) = - 6 and n = 15
The formula to find the nth term is
Substituting the values, we get
= -3 + (14) (-6)
= -3 + (14) (-6)
= -3 + (-84)
= -87
Hence the correct option is A
Determine the number of terms in the A.P.3,7,11,...407. Also ,find its 20th term from the end . | |||
| Right Option : B | |||
| View Explanation | |||
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