Question

Sum of 1 to n natural numbers is 36 then find the value of n.
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Answer 1

Answer:

1+2+3+4+5+6+7+8 = 36

n = 8

Answer 2

Answer:

a = 1

d = 1

Sn = 36

Sn = n/2 (2a + (n-1) d)

36 = n/2 (2(1) + (n-1) 1)

36×2 = n (2 + n-1 )

72 = n (n + 1)

72 = n² + n

0 = n² + n - 72

0 = n² + 9n - 8n - 72

0 = n(n+9) - 8(n+9)

0 = (n-8)(n+9)

n = -9 or 8

n = 8 ( n is not equal to -9)