Question

Determine the nth term of the AP whose 7th term is -1 and 16 term is 17

Answer 1

Answer:

a7 = a+6d= -1 ------------------ equation 1

a16= a+15d=17------------------equation 2

subtracting equation 2 from equation 1, we get

a+15d=17

a+6d= -1

- - +

—————————

0 + 9d= 18

d=2

now putting the value of d in equation 1, we get

a+ 6 (2)= -1

a+12= -1

a = -13

now an = a+ (n-1) d

an= -13 + (n-1) 2

= -13+ 2n-2

= 2n-15

this is the answer...