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The 20th term from the end of the AP, 3, 8 , 13,. ..... ,253 is​

User Omar Emam
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Given A.P = 3,8,13,...,253

Common difference = 8-3 = 5

The AP from the end = 253, 248,245,...,13,8,3

First term from the end = 253

Common difference = 248-253 = -5

We know that

an = a+(n-1)d

t20 = 253+(20-1)(-5)

→ t 20 = 253 +(19)(-5)

→ t 20 = 253-95

→ t 20 = 158

20th term from the end of the AP = 158

User Rich Catalano
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