Question

The first and sixth term of an Ap are 3 and 13 respectively find the sum of the first six terms

Answer 1

I av not seen wat i asked u pls help me out

Answer 2

just use the formulas you know
S_n = n/2 (a_1 + a_n)
S6 = 6/2 (3+13) = 48

Answer 3

Just use your formulas and definitions
we are told:
a = 3 and a + 5d = 13
so
3 + 5d = 13
5d = 10
d = 2

sum(6) = (6/2)(2(3) +5(2) ) = ....

or using the other formula:
sum(6) = 3(first + last) = 3(3 + 13) = ....

or the long way:
3 + 5 + 7 + 9 + 11 + 13 = ....

all 3 answers will be the same