Algebra · real student question

Solve the inequality 4x^2 - 4x + 1 > 0.

Question

Solve

4x24x+1>04x^2-4x+1>0

Step-by-step solution

  1. Match the perfect-square pattern with a non-unit leading term. Here 4x2=(2x)24x^2=(2x)^2 and 1=121=1^2, and the middle term checks out:

    2(2x)1=4x4x24x+1=(2x1)22\cdot(2x)\cdot 1=4x\quad\Longrightarrow\quad 4x^2-4x+1=(2x-1)^2

  2. Confirm with the discriminant. Δ=(4)24(4)(1)=1616=0\Delta=(-4)^2-4(4)(1)=16-16=0, so there is exactly one repeated root and no sign change.

  3. Reduce to a statement about a square.

    (2x1)2>0    2x10(2x-1)^2>0\iff 2x-1\neq 0

  4. Solve the excluded equation.

    2x1=0x=122x-1=0\quad\Longrightarrow\quad x=\frac12

    so every real number other than 12\tfrac12 satisfies the inequality.

  5. Check and compare with the unit-coefficient version. At x=12x=\tfrac12: 12+1=01-2+1=0, not >0>0 \checkmark. At x=0x=0: 1>01>0 \checkmark. The structure is identical to x22x+1>0x^2-2x+1>0, but the repeated root moves from 11 to 12\tfrac12 because the base is 2x12x-1 rather than x1x-1.

Answer

x12,i.e. (,12)(12,)x\neq\frac{1}{2},\qquad\text{i.e. }\left(-\infty,\tfrac12\right)\cup\left(\tfrac12,\infty\right)

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