What is the common difference of an AP in which a21 minus a7

1.	What is the common difference of an AP in which a21 minus a7
Answer» Plzzz complete the ques..... D=0 Question:\xa0What is the common difference of an A.P. in which a21-a7=84Answer:Let a is the first term and d is the common difference of an AP\xa0a21 = a + ( 21 -1)d = a + 20d\xa0a7 = a + (7 -1)d = a + 6d\xa0now,\xa0a +20d -a -6d = 84\xa014d = 84\xa0d = 6 ( answer) Write a20=a+19d and a7=a+6d and then solve it

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