Algebra · real student question

Solve (2x − 3)² − (x − 1)² = 0.

Question

Solve

(2x3)2(x1)2=0(2x-3)^2 - (x-1)^2 = 0

Step-by-step solution

  1. Recognise the difference-of-squares structure. Both terms are already perfect squares of linear expressions, so

    A2B2=(AB)(A+B)with A=2x3, B=x1A^2 - B^2 = (A - B)(A + B) \qquad \text{with } A = 2x - 3, \ B = x - 1

    No expansion is needed; the equation factors immediately.

  2. Form the first factor, distributing the minus sign.

    AB=(2x3)(x1)=2x3x+1=x2A - B = (2x - 3) - (x - 1) = 2x - 3 - x + 1 = x - 2

    The subtraction of 1-1 becomes +1+1; dropping that sign flip is the usual error and would give x4x - 4 instead.

  3. Form the second factor.

    A+B=(2x3)+(x1)=3x4A + B = (2x - 3) + (x - 1) = 3x - 4

    So the equation becomes

    (x2)(3x4)=0(x - 2)(3x - 4) = 0

  4. Solve each linear factor.

    x2=0  x=2,3x4=0  x=43x - 2 = 0 \ \Rightarrow \ x = 2, \qquad 3x - 4 = 0 \ \Rightarrow \ x = \frac{4}{3}

  5. Verify both. At x=2x = 2: (43)2(21)2=11=0 (4-3)^2 - (2-1)^2 = 1 - 1 = 0 \ \checkmark. At x=43x = \tfrac43: (833)2(431)2=1919=0 \left(\tfrac83 - 3\right)^2 - \left(\tfrac43 - 1\right)^2 = \tfrac19 - \tfrac19 = 0 \ \checkmark. Geometrically, (2x3)2=(x1)2(2x-3)^2 = (x-1)^2 means 2x3=x1|2x-3| = |x-1|, and the two roots are exactly the cases 2x3=x12x - 3 = x - 1 and 2x3=(x1)2x - 3 = -(x-1).

Answer

x=2orx=43x = 2 \quad \text{or} \quad x = \frac{4}{3}

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