Question

pls solve it or atleast explain the meaning of last line... ​

Answer 1

let the same common difference of two A.P's is d

given that the first term of first AP and second AP are 2 and 7 respectively then the AP is

2,2+d,2+2d,2+3d.... and

7,7+d,7+2d,7+3d.....

now 10th terms of first and second AP are 2+9d and 7+9d

d = 7+9d-(2+9d)=5

also 21st term of first and second AP are 2+20d and 7+20d

d=7+20d-(2+20d)=5

also if an and bn are nth term of 1st and 2nd ap

an=[7+(n-1)d]-[2+(n-1)d] =5

hence the difference between any two corresponding terms of such AP's

is the same as the difference between their first terms