Question

in an ap 3rd term is 7 and 7th term is 3 times the 3rd term then find the ap​

Answer 1

Answer:

An = a+(n-1) d

Now, put values and solve......

Answer 2

Given ,

The third term of AP is 7 and seventh term is 3 times of 3rd term

Let , The first term and common difference of AP be "a" and "d"

According to the question ,

a + 2d = 7 --- (i)

And

a + 6d = 3(a + 2d)

a + 6d = 3 × 7

a + d = 21 --- (ii)

Subtract eq (i) from eq (ii) , we get

a + d - (a + 2d) = 21 - 7

d - 2d = 14

d = -14

Put the value of d = -4 in eq (i) , we get

a + 2(-14) = 7

a - 28 = 7

a = 35

$\therefore \sf \underline{The \: AP \: is \: 35 , 21 , 7 , .... }$