Question

Find the number of terms of the A.P. 10,7,4,.........., - 62 *​

Answer 1

Answer:

Number of terms = 25 and -62 is the 25th term

Explanation:

a= 10

d = 7-10 = -3

tn = -62

tn = a+(n-1)d

-62 = 10 + (n-1)×-3

-62-10 = -3n+3

3n = 3+72

3n = 75

n = 75/3

n = 25

Answer 2

Question :

★Find the number of terms of the A.P. 10,7,4,.........., - 62 *.

Answer :

In this AP,

a = 10

d = 7-10 = 4-7 =(-3)

An / l = (-62)

Using the Formula for finding the last term of an AP

An/l = a + (n-1)d

-62 = 10 +(n-1)(-3)

-62-10 =(n-1)(-3)

-72 = (n-1)(-3)

Dividing both sides by (-3)

24 = n-1

n = 24+1

${\boxed{n=25}}$