Analyzing the Setup
The equation provided is x2−∣x∣−12=0. While it resembles a standard quadratic equation, the presence of the absolute value term ∣x∣ introduces a specific constraint that we must address carefully.
The Hidden Symmetry
The first step is to recognize the relationship between x2 and ∣x∣. For any real number x, the square of the number is identical to the square of its absolute value:
By substituting this identity into our original equation, we transform it into a quadratic form involving only the absolute value:
The Bridge of Substitution
To simplify the algebra, let us introduce a substitution variable. Let t=∣x∣.
Our equation now becomes a standard quadratic:
However, we must respect the gatekeeper constraint. Since t=∣x∣ and the absolute value of any real number is non-negative, we must enforce the condition:
Solving the Quadratic
We now factor the quadratic equation t2−t−12=0. We look for two numbers that multiply to −12 and add to −1. These numbers are −4 and 3.
The factored form is:
This yields two potential roots for t:
Final Calculation
We must now check these roots against our constraint t≥0. The value t=−3 is rejected because an absolute value cannot be negative.
This leaves us with the single valid solution:
Substituting back for x, we have ∣x∣=4. This implies that x can take two possible values:
x=4 or x=−4