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Answer:
- decreasing: (-∞, -3)
- increasing: (-3, ∞)
Step-by-step explanation:
The leading coefficient is positive, so you know the parabola opens upward.
The ratio -b/(2a) is -6/(2·1) = -3, so you know the axis of symmetry is x = -3. The function will be decreasing from negative infinity to the vertex at x = -3, and will be increasing from there to positive infinity. At the vertex (x=-3), the function is neither increasing nor decreasing.
- decreasing: (-∞, -3)
- increasing: (-3, ∞)
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Additional comment
For ax^2 +bx +c, the axis of symmetry is x=-b/(2a). The vertex (turning point) is on the axis of symmetry.
