Question

in an AP the common difference d and 7th term(A7) is 4 then find the first term

Answer 1

D=4 and A7=4
A7=a+(n-1)D
4=a+(7-1)4
4=a+6×4
4-24=a
so a=-20

Answer 2

so we have ,
        d = 4
        a7 = 4                                    } GIVEN
        n = 7 (for seventh term )
   a7 = a + (n-1)d
   4 = a + (6)4
    4 = a + 24
    a = -24+4
    a = -20..................
so , -20 is the 1st term of the given A.P