The problem presents the function $y = |x+2| - |2x-4|$. We want to understand this function, perhaps by simplifying it or finding its values for different ranges of $x$.

AlgebraAbsolute ValuePiecewise FunctionsFunction AnalysisInequalities
2025/5/25

1. Problem Description

The problem presents the function y=x+22x4y = |x+2| - |2x-4|. We want to understand this function, perhaps by simplifying it or finding its values for different ranges of xx.

2. Solution Steps

To analyze this function, we need to consider the cases when the expressions inside the absolute values are positive or negative.
Case 1: x+20x+2 \ge 0 and 2x402x-4 \ge 0. This means x2x \ge -2 and x2x \ge 2. Thus, x2x \ge 2.
In this case, x+2=x+2|x+2| = x+2 and 2x4=2x4|2x-4| = 2x-4.
So, y=(x+2)(2x4)=x+22x+4=x+6y = (x+2) - (2x-4) = x+2 - 2x + 4 = -x + 6.
Case 2: x+20x+2 \ge 0 and 2x4<02x-4 < 0. This means x2x \ge -2 and x<2x < 2. Thus, 2x<2-2 \le x < 2.
In this case, x+2=x+2|x+2| = x+2 and 2x4=(2x4)=2x+4|2x-4| = -(2x-4) = -2x+4.
So, y=(x+2)(2x+4)=x+2+2x4=3x2y = (x+2) - (-2x+4) = x+2 + 2x - 4 = 3x - 2.
Case 3: x+2<0x+2 < 0 and 2x402x-4 \ge 0. This means x<2x < -2 and x2x \ge 2. This case is impossible.
Case 4: x+2<0x+2 < 0 and 2x4<02x-4 < 0. This means x<2x < -2 and x<2x < 2. Thus, x<2x < -2.
In this case, x+2=(x+2)=x2|x+2| = -(x+2) = -x-2 and 2x4=(2x4)=2x+4|2x-4| = -(2x-4) = -2x+4.
So, y=(x2)(2x+4)=x2+2x4=x6y = (-x-2) - (-2x+4) = -x-2 + 2x - 4 = x - 6.
Therefore, the function can be written piecewise as:
y={x6if x<23x2if 2x<2x+6if x2y = \begin{cases} x-6 & \text{if } x < -2 \\ 3x-2 & \text{if } -2 \le x < 2 \\ -x+6 & \text{if } x \ge 2 \end{cases}

3. Final Answer

y={x6if x<23x2if 2x<2x+6if x2y = \begin{cases} x-6 & \text{if } x < -2 \\ 3x-2 & \text{if } -2 \le x < 2 \\ -x+6 & \text{if } x \ge 2 \end{cases}