Question

When 5th term and 8th term are 12 and 21 find first three term of an AP​

Answer 1

Answer:

Given 5th term of AP is 12

i.e, a5 = a + 4d

a + 4d = 12.......eq1

also the 8th term is 21

i.e, a8 = a + 7d

a + 7d = 21.... eq2

From equation 2 and 1 by elimination method

a = 0 & d = 3

so, a = 0

a2 = 0+3

a2 = 3

a3 = 0+ 2(3)

a3 = 6

therefore the first three terms of AP are 0, 3 & 6