Question

which term of AP 21,42,63,84 etc is 420

Answer 1

here a=21,d=21 and an=420
an=a+(n-1)*d
420=21+(n-1)*21
399=21n-21
420=21n
n=420/21
therefore (n=20)
20th term will be 420

Answer 2

Step-by-step explanation:

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