Question

sum of 1 to n natural number is 28 then find the value of n ​

Answer 1

Answer:

If the sum of 1 to n natural numbers is 36, then what is the value of n?

If the sum of 1 to n natural numbers is 36, then what is the value of n?

I’ll start by answering a more general question:

If 1+2+…+n=k, then 8k+1−−−−−√−12=n

In this case,

8×36+1−−−−−−−−√−12=289−−−√−12= 8

You may ask how I came up with this amazing way to undo the summing of the first n numbers.

I’m glad you asked!

Let the function T(n) be defined as giving the sum of the first n numbers. T(n) is often called the nth “triangular” number, because if you arrange objects in a triangle, like bowling p

Using S to represent the sum of the natural numbers from 1 to n, we have:

S = 1 + 2 + … + (n-1) + n [A]

We can express this in another way.

S = n + (n-1) + … + 2 + 1 [B]

Adding A + B:

2S = [1+n] + [2+(n-1)] + … + [(n-1)+2] + [n+1] = n(n+1)

As S = 36, 2S = 72

So, we need to solve the equation n(n+1) = 72.

There are two possible solutions to this equation:

n=8

n=-9

We can safely ignore the second answer as -9 is not a natural number.

Answer: n=8

Answer 2

Answer:

1+2+3+4+5+6+7=28

1-n=28

n=7

Please mark me as brainlist.