Question

Find the first term and common difference of the AP=-25,-20,-15.​​

Answer 1

The 7 term is the first negative term.

In the given question,

We can conclude that the first term

a = 25

And the common difference(d)

d = 20-25

d = -5

For finding the A.P:-

We can use the formula

An = a+(n-1)d

As we know:-

for the first negative term it should be less than 0.

So the required equation will be:

=a+(n-1)d<0

=25+(n-1)*(-5)<0

=(n-1)*(-5)<-25

=(n-1)>5

=n>6

Therefore:-

The first negative term is it's 7th term.