Subjects algebra

Quadratic Inequality 18A083

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Question: 6$x^2$ +x-2$\le$ 0
1. **State the problem:** Solve the inequality $$6x^2 + x - 2 \le 0$$. 2. **Identify the type of inequality:** This is a quadratic inequality of the form $$ax^2 + bx + c \le 0$$ where $$a=6$$, $$b=1$$, and $$c=-2$$. 3. **Find the roots of the quadratic equation:** Solve $$6x^2 + x - 2 = 0$$ using the quadratic formula: $$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$ Substitute values: $$x = \frac{-1 \pm \sqrt{1^2 - 4 \times 6 \times (-2)}}{2 \times 6} = \frac{-1 \pm \sqrt{1 + 48}}{12} = \frac{-1 \pm \sqrt{49}}{12}$$ $$x = \frac{-1 \pm 7}{12}$$ 4. **Calculate the two roots:** $$x_1 = \frac{-1 - 7}{12} = \frac{-8}{12} = -\frac{2}{3}$$ $$x_2 = \frac{-1 + 7}{12} = \frac{6}{12} = \frac{1}{2}$$ 5. **Determine the intervals to test:** The roots divide the number line into three intervals: - $$(-\infty, -\frac{2}{3})$$ - $$[-\frac{2}{3}, \frac{1}{2}]$$ - $$(\frac{1}{2}, \infty)$$ 6. **Test the sign of the quadratic in each interval:** Since $$a=6 > 0$$, the parabola opens upwards. - For $$x$$ less than $$-\frac{2}{3}$$, the quadratic is positive. - Between $$-\frac{2}{3}$$ and $$\frac{1}{2}$$, the quadratic is less than or equal to zero. - For $$x$$ greater than $$\frac{1}{2}$$, the quadratic is positive. 7. **Write the solution:** $$\boxed{-\frac{2}{3} \le x \le \frac{1}{2}}$$ This is the set of $$x$$ values that satisfy the inequality.