Question

if an AP the common difference and seventh term is 4 then find the first term

Answer 1

a7=4, d=4
a +6d=4    (nth term = a +(n-1)d)
a +24=4
a= -20 = first term of AP

Answer 2

d=4,a7=4
a7=a+(n-1)d
4=a+(7-1)4
4=a+24
a=4-24=-20
therefore first term is -20