Question

In an AP, if the common difference (d) = - 4 , and the seventh term (a7) = 4 , then find the first term.

Answer 1

a7=a+6d
a+6d=4
d=-4(given)
a+6(-4)=4
a-24=4
a=4+24
a=28
therefore, first term of an AP is 28

Answer 2

d=-4
T7=4
T1=a=?
a+n-1)d
T7=a+6d
4=a-24
a=24+4
a=28