Example

Example: Solving x26x+8<0x^2 - 6x + 8 < 0 Graphically

To solve the quadratic inequality x26x+8<0x^2 - 6x + 8 < 0 graphically, first ensure it is in standard form. Next, graph the corresponding function f(x)=x26x+8f(x) = x^2 - 6x + 8, an upward-facing parabola with its vertex at (3,1)(3, -1), a yy-intercept at (0,8)(0, 8), and xx-intercepts at (2,0)(2, 0) and (4,0)(4, 0). Finally, determine the solution from the graph. The inequality asks for the values of xx that make the function less than 00, which means identifying where the parabola is strictly below the xx-axis. This occurs between the xx-intercepts. Since the inequality is strictly less than, the values 22 and 44 are not included. Thus, the solution in interval notation is (2,4)(2, 4).

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Updated 2026-05-25

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