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The set of all real numbers x for which x2−∣x+2∣+x>0x^2 - |x + 2| + x > 0, is

Solution

✅ Correct Option: 2

From the given data, x2−∣x+2∣+x>0x^2 - |x + 2| + x > 0

We can discuss this problem by observing two different cases.

Case 1: When (x+2)≥0(x + 2) \geq 0

Therefore, x2−(x+2)+x>0x^2 - (x + 2) + x > 0

Hence, x2−2>0x^2 - 2 > 0

x2>2x^2 > 2

⇒x<−2\Rightarrow x < -\sqrt{2} or x>2x > \sqrt{2}

Hence, x∈(−∞,−2)∪(2,∞)x \in (-\infty, -\sqrt{2}) \cup (\sqrt{2}, \infty) ...... (1)(1)

Case 2: When (x+2)<0(x + 2) < 0

Then x2+x+2+x>0x^2 + x + 2 + x > 0

So, x2+2x+2>0x^2 + 2x + 2 > 0

This gives (x+1)2+1>0(x + 1)^2 + 1 > 0 and this is true for every xx (Because (x+1)2≥0⇒(x+1)2+1≥1(x + 1)^2 \geq 0 \Rightarrow (x + 1)^2 + 1 \geq 1 )

Hence, x∈(−∞,∞)x \in (-\infty, \infty) ...... (2)(2)

From equations (1)(1) and (2)(2), we take the intersection, hence we get x∈(−∞,−2)∪(2,∞)x \in (-\infty, -\sqrt{2}) \cup (\sqrt{2}, \infty).

Therefore, x∈(−∞,−2)∪(2,∞)x \in (-\infty, -\sqrt{2}) \cup (\sqrt{2}, \infty) is the required answer.

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