Question

Determine the first term of an AP whose third term is 5 and the 7th term is 9.​

Answer 1

Answer:

First Term = 3

Step-by-step explanation:

a + 2d = 5 (I)

a + 6d = 9 (ii)

ii - i

4d = 4

d = 4

Put in equation i

a + 2(4) = 5

a = 5 - 8

a = -3

Hope it helps you

Answer 2

Answer:

3

Step-by-step explanation:

$Third term = a + 2d = 5\\Seventhterm = a + 6d = 9$

using elemination method,

$a - a + 6d - 2d = 9 - 5\\4d = 4\\d = 1$

putting the value of d in in one of the equations

$a = 5 - 2(1)\\a = 5 - 2\\a = 3$

hope this helps