Problem:
The sum of a natural number and its square is 156. Find the number.
Solution:
Let's assume the natural number as 'x'. Then we have the following equation:
x + x² = 156
Now we need to solve this equation to find the value of x.
Method 1: Quadratic Formula
This equation is a quadratic equation. We can solve it using the quadratic formula:
x = (-b ± sqrt(b² - 4ac)) / 2a
Here, a = 1, b = 1, and c = -156
Substituting these values in the formula, we get:
x = (-1 ± sqrt(1² - 4(1)(-156))) / 2(1)
x = (-1 ± sqrt(625)) / 2
x = (-1 ± 25) / 2
Therefore, x = 12 or x = -13. But we know that x is a natural number, so x can only be 12.
Method 2: Factoring
We can also solve this equation by factoring:
x + x² = 156
x² + x - 156 = 0
(x + 13)(x - 12) = 0
Therefore, x = 12 or x = -13. But we know that x is a natural number, so x can only be 12.
Answer:
The natural number is 12.