algebra · worked example

Solve x² - 7x + 12 = 0 — x = 3 or x = 4

Method: 因式分解. Verified step-by-step solution with our free AI math solver.
Problem

x27x+12=0x^2 - 7x + 12 = 0

Step-by-step solution

  1. 找出兩個數,使其相乘為 1212 且相加為 7-7

  2. 兩數皆須為負(乘積為正、和為負):3-34-4 成立,因為 (3)(4)=12(-3)(-4) = 123+(4)=7-3 + (-4) = -7

  3. 因式分解:(x3)(x4)=0(x - 3)(x - 4) = 0

  4. 令每個因式為零:x=3x = 3x=4x = 4

Answer

x=3orx=4x = 3 \quad \text{or} \quad x = 4

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