Question

If the nth term of an AP is 9-5n . Find the sum of the first three term is ?

Answer 1

Given:

We have nth term of A.P is given by 9-5n.

To Find:

Sum of first three terms?

Step-by-step explanation:

• Since we have nth term of A.P is given by 9-5n.

• For first term we will put n=1 in given equation

               $a_1=9-5(1)=4$

• For second term we will put n=2 in given equation

              $a_2=9-5(2)=9-10=-1$

• For third term we will put n=3 in given equation

              $a_3=9-5(3)=9-15=-6$

Thus sum of first three terms will be

            $=a_1+a_2+a_3=4-1-6=4-7=-3$

Hence, sum of three terms will be -3