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The number of real roots of the equation...

The number of real roots of the equation `|x|^(2) -3|x| + 2 = 0`, is

A

1

B

2

C

3

D

4

Text Solution

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The correct Answer is:
To find the number of real roots of the equation \( |x|^2 - 3|x| + 2 = 0 \), we will analyze the equation based on the definition of absolute value. ### Step 1: Rewrite the equation The given equation is: \[ |x|^2 - 3|x| + 2 = 0 \] Let \( y = |x| \). The equation can be rewritten as: \[ y^2 - 3y + 2 = 0 \] ### Step 2: Factor the quadratic equation Next, we will factor the quadratic equation: \[ y^2 - 3y + 2 = (y - 1)(y - 2) = 0 \] This gives us the solutions: \[ y - 1 = 0 \quad \text{or} \quad y - 2 = 0 \] Thus, we have: \[ y = 1 \quad \text{or} \quad y = 2 \] ### Step 3: Convert back to \( x \) Since \( y = |x| \), we have two cases for each solution: 1. For \( y = 1 \): - \( |x| = 1 \) gives \( x = 1 \) or \( x = -1 \) 2. For \( y = 2 \): - \( |x| = 2 \) gives \( x = 2 \) or \( x = -2 \) ### Step 4: List all the real roots The real roots of the original equation are: - From \( y = 1 \): \( x = 1, -1 \) - From \( y = 2 \): \( x = 2, -2 \) Thus, the real roots are: \[ x = 1, -1, 2, -2 \] ### Step 5: Count the number of real roots In total, we have 4 real roots: \( 1, -1, 2, -2 \). ### Conclusion The number of real roots of the equation \( |x|^2 - 3|x| + 2 = 0 \) is **4**. ---
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