Question

find the sum of all multiples of 7 lying between 500 and 800

Answer 1

Step-by-step explanation:

The list of numbers between 500 and 800 that are multiples of 7 is :

504, 511, 518,.........................798.

Clearly the above list is in AP with first term, a = 504 and common difference, d = 7.

Let the nth term of AP is 798.

an = a + (n - 1)d

⇒ 798 = 504 + (n - 1)(7)

⇒ n = 43

sum of first 43 terms of the above AP is given by,

Answer 2

Answer:

Step-by-step

the answer is x or variable a number which we do not know is variable

ok