Question

if the common difference of an ap is 5then what is T18 T13?

Answer 1

Common difference = d = 5
first term = a = a
number of the term = n

Tn = a+(n-1)d
T18 = a+(18-1)5
T18 = a+(17)5
T18 = a+85

Tn = a+(n-1)d
T13 = a+(13-1)5
T13 = a+(12)5
T13 = a+60

so,
T18 - T13
= (a+85)-(a+60)
= a+85-a-60
= 85-60
= 25

so 25 is the answer

Answer 2

Hi

Here is ur answer

Given:

   d = 5

Tn = a +(n-1)d

T18 = a+ (18-1)5

      = a+17*5

T18 = a+85

T13 = a +(13-1)5

     =a+12*5

  T13 =a+60

Therefore,

T18 - T13 = a+85 _ (a+60)

              = a+85 - a -60

-a and +a get cancelled out , then

 T18 - T13 = 25

Hope it helps U