The first and thirteenth terms of an arithmetic sequence are 7/9 and 4/5, respectively. What is the seventh term?

Here,

Let the first term be denoted by a and commom difference by b.

Now,

T1 = a

= 7/9

T13 = a + 12 d

or, 4/5 = 7/9 + 12d

or 12d = 4/5 -7/9

or, 12d = 1/45

or, d = 1/410.

then,

T7= a + 6d

= 7/9 + 1/410

= 2879/2870

Please check the answer and tell me whether it is correct or not.

step-by-step explanation:

given that there are two triangles j'k'l' and jkl>

the former is got by dilating the second one.

when drawn on a grid, (graph paper) coordinates of vertices of first triangle is

(6,12)j, (9,6)k and (12,9)l

side jk has length = distance between j and k

=

side j'k'=distance between j' and k'

=

ie j'k'l' has sides 1/3 of that of corresponding sides of jkl.

hence scale factor of 1/3 is used to get j'k'l'from jkl