How Do You Find the Y-Coordinate of a Parabola's Vertex?

In summary, the vertex of a parabola is the highest or lowest point on the parabola and is found where the parabola changes direction from increasing to decreasing or vice versa. The vertex can be found using the formula x = -b/2a or by completing the square. The axis of symmetry is a vertical line that passes through the vertex and the vertex can be at the origin for certain equations. There are two ways to find the vertex, both of which will give the same result.
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Homework Statement

Sorry for such an elementary question, but I'm struggling thru Int Alg. Today's nightmare involves a downward parabola. An arch supporting a bridge has the equation y=-0.0022x^2 + 1.578x + 0. Position of left side parabolic arch is (0,0). Using x = -b/2a, I calculated the symmetrical point of the parabola at (358.6363,0). If this is correct, the vertex x-coordinate is 179.31815. I'm stuck at finding the y coordinate of the vertex. Any help would be greatly appreciated.



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The Attempt at a Solution

 
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You know that y=-0.0022x^2 + 1.578x. What is y when x = 179.31815?
 

FAQ: How Do You Find the Y-Coordinate of a Parabola's Vertex?

What is the vertex of a parabola?

The vertex of a parabola is the point where the parabola changes direction from increasing to decreasing or vice versa. It is the highest or lowest point on the parabola depending on whether it opens upwards or downwards.

How do you find the vertex of a parabola?

To find the vertex of a parabola, you can use the formula x = -b/2a, where a and b are the coefficients of the quadratic equation in the form ax^2 + bx + c. This value of x represents the x-coordinate of the vertex. To find the y-coordinate, you can substitute this value of x into the original equation and solve for y.

What is the relationship between the vertex and the axis of symmetry?

The axis of symmetry is a vertical line that passes through the vertex and divides the parabola into two symmetrical halves. The equation of the axis of symmetry is x = -b/2a, which is the same as the x-coordinate of the vertex. Therefore, the vertex and the axis of symmetry are the same point on the coordinate plane.

Can a parabola have a vertex at the origin?

Yes, a parabola can have a vertex at the origin. This occurs when the quadratic equation is in the form y = ax^2, where a is the coefficient and the y-intercept is 0. In this case, the vertex is at (0,0) and the axis of symmetry is the y-axis.

How many ways are there to find the vertex of a parabola?

There are two main ways to find the vertex of a parabola. The first is by using the formula x = -b/2a, as mentioned earlier. The second method is by completing the square, where you manipulate the quadratic equation into the form a(x-h)^2 + k, where (h,k) represents the coordinates of the vertex. Both methods will give you the same result.

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