Question

in an AP if the common difference is equal to -4 and the 7th term is 7 is food then find the first term

Answer 1

given
d=(-4)
a7=4

we know that
an=a+(n-1)d
a7=a+6d
4=a+6(-4)
4=a-24
4+24=a
a=28

therefore the first term of the AP is 28

Answer 2

we know that
common difference which is d is equal to - 4
7th term = a+6d
But 7th term = 4
Now substitute d= -4
a + 6(-4) = 4
a - 24=4
a = 28
Therefore first term = a = 28