algebra · worked example

Solve 2x² - 3x - 2 = 0

Method: 二次公式. Verified step-by-step solution with our free AI math solver.
Problem

2x23x2=02x^2 - 3x - 2 = 0

Step-by-step solution

  1. 辨識 a=2a = 2b=3b = -3c=2c = -2

  2. 計算判別式:Δ=(3)24(2)(2)=9+16=25\Delta = (-3)^2 - 4(2)(-2) = 9 + 16 = 25

  3. 套用二次公式:x=3±2522=3±54x = \frac{3 \pm \sqrt{25}}{2 \cdot 2} = \frac{3 \pm 5}{4}

  4. 兩個解:x1=3+54=2x_1 = \frac{3 + 5}{4} = 2x2=354=12x_2 = \frac{3 - 5}{4} = -\frac{1}{2}

Answer

x=2orx=12x = 2 \quad \text{or} \quad x = -\tfrac{1}{2}

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