Question

the 4th and 8th term of AP are in the ratio 1:2 and the 10th term is 30 find the common difference and first term right AP ​

Answer 1

Answer:

see nth term if an ap is given by a+(n-1)d that means 4th term =a+3d and 8th term=a+7d

a+3d/a+7d=1/2 and a+9d=30 let us suppose a and d are 3 we get the ans correct by supposition a=3 d=3

Answer 2

Answer:

a4 /a8 = 1/2

(a+3d)/(a+7d) = 1/2

2a + 6d = a+7d

a = d

if

a10 = 30

a + 9d = 30

a +9(a) = 30

10a = 30

a = 30/10

a = 3

as

d = a

so d= 3

thus common difference is 3

and first term is 3