Question

find the some of all integers between 84 and 719 which are multiples of 5​

Answer 1

Answer:

the sum of all integers between 84 and 719, which are multiples of 5 is 50800.

Step-by-step explanation:

Integers between 84 and 719, which are multiples of 5 are 85, 90,95 ,...... 715

Here,  

a = 85, d = 5, an( l) = 715

By using the formula ,an = a + (n - 1)d

715 = 85 + (n -1)5

715 - 85 =  5(n -1)

630 = 5(n -1)

n -1 = 630/5

n -1 = 126

n = 126 + 1  

n = 127

By using the formula ,Sum of nth terms , Sn = n/2 [a + l]

⇒ S127 = 127/2 (a + l)

⇒ S127 = 127/2 (85 + 715)

⇒ S127 = 127/2 (800)  

⇒ S127  = 127 × 400

⇒ S127 = 50800

Answer 2

Step-by-step explanation:

5,85,90,etc are some examples of your question