Question

DECIDE !!!!!!!!!!!!!

Answer 1

• 55

Explanation:

Use the identity for the sum of squares of n natural numbers:

• Sₙ² = n(n + 1)(2n + 1)/6

Since we have the sum, 56980:

• n(n + 1)(2n + 1)/6 = 56980
• (n² + n)(2n + 1) = 56980*6
• 2n³ + 3n² + n - 341880 = 0

Solve the equation graphically to get a natural solution of n = 55