Question

In an AP : a1 ,a2 ,...... an if a1= 21 , a2 = 42 ,an =420
a. n=18
b. n=19
c. n=21
d. n=20​

Answer 1

Answer:

n=20

Step-by-step explanation:

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Answer 2

Answer:

HEy maTe here's ur answer ___✌️❤️✌️

n=20

$an = a + (n - 1)d \\ 420 = 21 + (n - 1)d \\ n = \frac{420}{21} \\ n = 20$

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