The first term of an AP is 5, the last term is 45 and the sum is 400.

1.	The first term of an AP is 5, the last term is 45 and the sum is 400. Find the number of termsand the common difference.5.
Answer» Given for an APFirst term a = 5, Last term an = 45, Sum = 400 Let common difference is d and number of terms is n Sum of n terms400 = n/2(a + l)400 = n/2(5 + 45)n = 800/50 = 16 an = a + (n-1)d45 = 5 + 15dd = 40/15 = 8/3

The first term of an AP is 5, the last term is 45 and the sum is 400. Find the number of termsand the common difference.5.

Answer»

Given for an APFirst term a = 5, Last term an = 45, Sum = 400

Let common difference is d and number of terms is n

Sum of n terms400 = n/2(a + l)400 = n/2(5 + 45)n = 800/50 = 16

an = a + (n-1)d45 = 5 + 15dd = 40/15 = 8/3