Question

2. Sum of the first 21 terms of an AP is 1071. Wh
is the first term if the common difference is 6?
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Answer 1

Answer:

s21=1071.

d=6.

a=?.

sn=n/2[2a+(n-1)d].

s21=21/2[2a+(21-1)(6)].

1071=21[a+(20)(6)].

1071=21[a+120].

1071/21=a+120.

51=a+120.

a=51-120.

a=-69. (Because +×-=- & largest number is important).

I think this is your answer.

Answer 2

Answer:

Step-by-step explanation:

An= a+ (n-1)d

1071 = a + 20× 6

1071 = a+ 120

a= 1071 - 120

a = 951

Therefore, first term is 951