What is how to graph a parabola?
Here's how to graph a parabola:
To graph a parabola, you'll typically want to follow these steps:
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Identify the Form of the Equation: Parabolas can be represented in different forms. The most common are:
- Standard Form: y = ax² + bx + c or x = ay² + by + c (opens left or right)
- Vertex Form: y = a(x - h)² + k or x = a(y - k)² + h (opens left or right)
where (h,k) is the vertex of the parabola.
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Determine the Direction of Opening:
- If 'a' > 0 in y = ax² + bx + c or y = a(x - h)² + k, the parabola opens upward.
- If 'a' < 0 in y = ax² + bx + c or y = a(x - h)² + k, the parabola opens downward.
- If 'a' > 0 in x = ay² + by + c or x = a(y - k)² + h, the parabola opens to the right.
- If 'a' < 0 in x = ay² + by + c or x = a(y - k)² + h, the parabola opens to the left.
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Find the Vertex:
- Standard Form (y = ax² + bx + c): The x-coordinate of the vertex is given by x = -b / 2a. Substitute this x-value into the equation to find the corresponding y-value.
- Vertex Form (y = a(x - h)² + k): The vertex is simply (h, k).
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Find the Axis of Symmetry:
- The axis%20of%20symmetry is a vertical line that passes through the vertex. Its equation is x = h (where (h,k) is the vertex). For parabolas that open sideways, the axis of symmetry is a horizontal line with the equation y=k.
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Find the Intercepts (if possible and helpful):
- x-intercept(s): Set y = 0 in the equation and solve for x. These are the points where the parabola crosses the x-axis. You might need to use the quadratic%20formula if the equation doesn't factor easily.
- y-intercept: Set x = 0 in the equation and solve for y. This is the point where the parabola crosses the y-axis.
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Find Additional Points (if needed):
- Choose some x-values on either side of the vertex and substitute them into the equation to find the corresponding y-values. This will give you more points to plot and help you sketch a more accurate parabola.
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Plot the Points and Sketch the Parabola:
- Plot the vertex, intercepts, and any additional points you've found. Draw a smooth curve through the points, keeping in mind the direction of opening and the axis%20of%20symmetry. The parabola should be symmetrical about the axis of symmetry.
Key elements to consider:
- Focus and Directrix: These define the parabola geometrically. The focus is a point, and the directrix is a line. Every point on the parabola is equidistant from the focus and the directrix. The vertex is exactly halfway between the focus and the directrix.