Math Problem Statement

The sum of the squares of two consecutive natural numbers is 313. Find the numbers.

Solution

The problem states:

"The sum of the squares of two consecutive natural numbers is 313. Find the numbers."

Solution:

Let the two consecutive natural numbers be xx and x+1x+1.

  1. The square of xx is x2x^2, and the square of x+1x+1 is (x+1)2(x+1)^2.
  2. The sum of their squares is given as: x2+(x+1)2=313x^2 + (x+1)^2 = 313
  3. Expanding (x+1)2(x+1)^2: x2+x2+2x+1=313x^2 + x^2 + 2x + 1 = 313
  4. Combine like terms: 2x2+2x+1=3132x^2 + 2x + 1 = 313
  5. Subtract 313 from both sides: 2x2+2x312=02x^2 + 2x - 312 = 0
  6. Simplify by dividing through by 2: x2+x156=0x^2 + x - 156 = 0

Solve the Quadratic Equation:

x2+x156=0x^2 + x - 156 = 0 Using the quadratic formula: x=b±b24ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} Here, a=1a = 1, b=1b = 1, c=156c = -156.

  1. Calculate the discriminant: Δ=b24ac=124(1)(156)=1+624=625\Delta = b^2 - 4ac = 1^2 - 4(1)(-156) = 1 + 624 = 625
  2. Solve for xx: x=1±6252x = \frac{-1 \pm \sqrt{625}}{2} x=1±252x = \frac{-1 \pm 25}{2}
  3. Two solutions: x=1+252=242=12x = \frac{-1 + 25}{2} = \frac{24}{2} = 12 x=1252=262=13x = \frac{-1 - 25}{2} = \frac{-26}{2} = -13

Since xx must be a natural number, x=12x = 12.

Final Answer:

The two consecutive natural numbers are 12 and 13.

Verification:

122+132=144+169=31312^2 + 13^2 = 144 + 169 = 313

The solution is correct.


Would you like a step-by-step explanation or help with a related concept?

Related Questions:

  1. What are consecutive numbers, and how do they differ from consecutive even/odd numbers?
  2. How does the quadratic formula work, and when is it used?
  3. Can this problem be solved without using the quadratic formula? If so, how?
  4. What happens if the given sum is not a perfect square?
  5. Why is it necessary to reject negative values in this context?

Tip:

When solving quadratic equations, always verify the solution by substituting the values back into the original equation!

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Natural Numbers

Formulas

Quadratic equation formula: ax^2 + bx + c = 0

Theorems

Quadratic formula

Suitable Grade Level

Grades 7-9