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What is the number of real solutions of ...

What is the number of real solutions of
`|x^(2) - x-6|=x+2`?

A

4

B

3

C

2

D

1

Text Solution

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The correct Answer is:
To solve the equation \( |x^2 - x - 6| = x + 2 \), we will consider two cases based on the definition of absolute value. ### Step 1: Identify the cases for the absolute value The expression inside the absolute value, \( x^2 - x - 6 \), can be either positive or negative. We will consider two cases: 1. Case 1: \( x^2 - x - 6 \geq 0 \) 2. Case 2: \( x^2 - x - 6 < 0 \) ### Step 2: Solve Case 1 (\( x^2 - x - 6 \geq 0 \)) In this case, we can remove the absolute value: \[ x^2 - x - 6 = x + 2 \] Rearranging the equation gives: \[ x^2 - x - x - 6 - 2 = 0 \implies x^2 - 2x - 8 = 0 \] ### Step 3: Factor the quadratic equation Now we will factor the quadratic: \[ x^2 - 2x - 8 = (x - 4)(x + 2) = 0 \] Setting each factor to zero gives us: \[ x - 4 = 0 \implies x = 4 \] \[ x + 2 = 0 \implies x = -2 \] ### Step 4: Check which solutions are valid for Case 1 We need to check if these solutions satisfy the condition \( x^2 - x - 6 \geq 0 \): - For \( x = 4 \): \[ 4^2 - 4 - 6 = 16 - 4 - 6 = 6 \geq 0 \quad \text{(valid)} \] - For \( x = -2 \): \[ (-2)^2 - (-2) - 6 = 4 + 2 - 6 = 0 \quad \text{(valid)} \] ### Step 5: Solve Case 2 (\( x^2 - x - 6 < 0 \)) In this case, we have: \[ -(x^2 - x - 6) = x + 2 \] This simplifies to: \[ -x^2 + x + 6 = x + 2 \] Rearranging gives: \[ -x^2 + x - x + 6 - 2 = 0 \implies -x^2 + 4 = 0 \implies x^2 = 4 \] Taking the square root gives: \[ x = 2 \quad \text{or} \quad x = -2 \] ### Step 6: Check which solutions are valid for Case 2 We need to check if these solutions satisfy the condition \( x^2 - x - 6 < 0 \): - For \( x = 2 \): \[ 2^2 - 2 - 6 = 4 - 2 - 6 = -4 < 0 \quad \text{(valid)} \] - For \( x = -2 \): \[ (-2)^2 - (-2) - 6 = 4 + 2 - 6 = 0 \quad \text{(not valid)} \] ### Step 7: Summary of valid solutions The valid solutions we found are: - From Case 1: \( x = 4 \) and \( x = -2 \) - From Case 2: \( x = 2 \) Thus, the unique solutions are \( x = 4, -2, 2 \). ### Conclusion The total number of real solutions is **3**.

To solve the equation \( |x^2 - x - 6| = x + 2 \), we will consider two cases based on the definition of absolute value. ### Step 1: Identify the cases for the absolute value The expression inside the absolute value, \( x^2 - x - 6 \), can be either positive or negative. We will consider two cases: 1. Case 1: \( x^2 - x - 6 \geq 0 \) 2. Case 2: \( x^2 - x - 6 < 0 \) ### Step 2: Solve Case 1 (\( x^2 - x - 6 \geq 0 \)) ...
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