Animated Solution for Mathematics - Quadratic Equations: The set of all real numbers x for which x2−∣x+2∣+x>0, is
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Visualized Solution
The Modulus Critical Point
The inequality is x2−∣x+2∣+x>0.
The modulus term ∣x+2∣ changes its sign at x=−2.
We must split the real number line into two distinct regions.
Defining the Two Cases
Case 1:x≥−2 (Right side of the critical point).
Case 2:x<−2 (Left side of the critical point).
Case 1 Setup (x≥−2)
For x≥−2, the expression inside the modulus is non-negative.
Therefore, ∣x+2∣=(x+2).
Substitute into the inequality: x2−(x+2)+x>0.
Simplifying Case 1
Expand the bracket: x2−x−2+x>0.
The x terms cancel out.
Simplified inequality: x2−2>0.
Solving x2−2>0
The equation x2−2=0 has roots at x=−2 and x=2.
The parabola opens upwards, so it is positive outside the roots.
Solution for the quadratic: x<−2 or x>2.
Validating Case 1 Solution
We must intersect x∈(−∞,−2)∪(2,∞) with our initial condition x≥−2.
Valid interval for Case 1: x∈[−2,−2)∪(2,∞).
Case 2 Setup (x<−2)
For x<−2, the expression inside the modulus is negative.
Therefore, ∣x+2∣=−(x+2).
Substitute into the inequality: x2−(−(x+2))+x>0.
Simplifying Case 2
The double negative becomes positive: x2+(x+2)+x>0.
Combine like terms: x2+2x+2>0.
Analyzing x2+2x+2>0
Let's check the discriminant D=b2−4ac.
D=(2)2−4(1)(2)=4−8=−4.
Since D<0 and a=1>0, the quadratic is always positive.
Validating Case 2 Solution
The inequality holds for all real numbers.
But we must intersect with our Case 2 condition: x<−2.
Valid interval for Case 2: x∈(−∞,−2).
Combining the Intervals
We unite the solutions from both cases.
Case 2 gives (−∞,−2).
Case 1 gives [−2,−2)∪(2,∞).
The point x=−2 perfectly bridges the first two intervals.
Final Solution Set
The combined continuous interval is (−∞,−2).
The right interval remains (2,∞).
Final Answer: x∈(−∞,−2)∪(2,∞).
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The Sigma Insight: Solution of Quadratic Equations
Solution Diagram
Analyzing the Setup
The inequality x2−∣x+2∣+x>0 contains an absolute value term that changes behavior at the critical point x=−2. To solve this, we must partition the number line into two distinct regions based on the sign of the expression inside the modulus.
Phase 1
The Right Side (x≥−2)
In the region where x≥−2, the expression x+2 is non-negative. By the definition of the modulus, ∣x+2∣=x+2.
Substituting this into the inequality, we obtain:
x2−(x+2)+x>0
Simplifying the expression:
x2−x−2+x>0
x2−2>0
The roots of x2−2=0 are x=±2. Since the parabola y=x2−2 opens upwards, the inequality holds for x<−2 or x>2.
Applying the boundary condition x≥−2, we find the intersection:
[−2,−2)∪(2,∞)
Phase 2
The Left Side (x<−2)
Now, we consider the region where x<−2. Here, x+2 is negative, so the modulus negates the expression: ∣x+2∣=−(x+2).
Substituting this into the original inequality:
x2−(−(x+2))+x>0
x2+x+2+x>0
x2+2x+2>0
To analyze this quadratic, we calculate the discriminant D:
D=(2)2−4(1)(2)=4−8=−4
Since D<0 and the leading coefficient is positive, the quadratic x2+2x+2 is always positive for all real x. Given our condition x<−2, the solution for this case is:
(−∞,−2)
Phase 3
The Grand Synthesis
We now combine the solutions from both cases using the union operator. From Case 1, we have [−2,−2)∪(2,∞), and from Case 2, we have (−∞,−2).
The point x=−2 acts as a bridge, connecting (−∞,−2) and $