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The solution of |x^(2) + 3x|+x^(2)-2 ge ...

The solution of `|x^(2) + 3x|+x^(2)-2 ge 0` is `

A

`(-oo,1)`

B

(0,1)

C

`(-oo,-(2)/(3)]cup[(1)/(2),oo)`

D

None of these

Text Solution

AI Generated Solution

The correct Answer is:
To solve the inequality \( |x^2 + 3x| + x^2 - 2 \geq 0 \), we will break it down into cases based on the expression inside the absolute value. ### Step 1: Identify Cases for the Absolute Value The expression \( |x^2 + 3x| \) can be split into two cases: 1. Case 1: \( x^2 + 3x \geq 0 \) 2. Case 2: \( x^2 + 3x < 0 \) ### Step 2: Solve Case 1 In Case 1, since \( x^2 + 3x \geq 0 \), we can remove the absolute value: \[ x^2 + 3x + x^2 - 2 \geq 0 \] This simplifies to: \[ 2x^2 + 3x - 2 \geq 0 \] ### Step 3: Factor the Quadratic To solve \( 2x^2 + 3x - 2 \geq 0 \), we can factor it: \[ 2x^2 + 4x - x - 2 \geq 0 \implies (2x - 1)(x + 2) \geq 0 \] ### Step 4: Find Critical Points The critical points are found by setting the factors to zero: 1. \( 2x - 1 = 0 \) gives \( x = \frac{1}{2} \) 2. \( x + 2 = 0 \) gives \( x = -2 \) ### Step 5: Test Intervals We will test the intervals determined by the critical points: - Interval 1: \( (-\infty, -2) \) - Interval 2: \( (-2, \frac{1}{2}) \) - Interval 3: \( (\frac{1}{2}, \infty) \) Using a test point from each interval: 1. For \( x = -3 \): \( (2(-3) - 1)(-3 + 2) = (-7)(-1) > 0 \) (valid) 2. For \( x = 0 \): \( (2(0) - 1)(0 + 2) = (-1)(2) < 0 \) (invalid) 3. For \( x = 1 \): \( (2(1) - 1)(1 + 2) = (1)(3) > 0 \) (valid) Thus, the solution for Case 1 is: \[ x \in (-\infty, -2] \cup [\frac{1}{2}, \infty) \] ### Step 6: Solve Case 2 In Case 2, since \( x^2 + 3x < 0 \), we have: \[ -(x^2 + 3x) + x^2 - 2 \geq 0 \] This simplifies to: \[ -3x - 2 \geq 0 \implies 3x + 2 \leq 0 \implies x \leq -\frac{2}{3} \] ### Step 7: Find the Range for Case 2 From Case 2, we also have the condition \( x^2 + 3x < 0 \) which factors to: \[ x(x + 3) < 0 \] The critical points are \( x = 0 \) and \( x = -3 \). Testing intervals: 1. For \( x = -2 \): \( (-2)(-2 + 3) > 0 \) (invalid) 2. For \( x = -4 \): \( (-4)(-4 + 3) > 0 \) (valid) 3. For \( x = -1 \): \( (-1)(-1 + 3) < 0 \) (valid) Thus, the solution for Case 2 is: \[ x \in (-3, 0) \] ### Step 8: Combine Solutions Now we combine the solutions from both cases: - From Case 1: \( (-\infty, -2] \cup [\frac{1}{2}, \infty) \) - From Case 2: \( (-3, 0) \) The combined solution is: \[ x \in (-\infty, -2] \cup (-3, 0) \cup [\frac{1}{2}, \infty) \] ### Final Answer Thus, the solution to the inequality \( |x^2 + 3x| + x^2 - 2 \geq 0 \) is: \[ (-\infty, -2] \cup (-3, 0) \cup [\frac{1}{2}, \infty) \]
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