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HELP What is Vertex?
- Thread starter klk
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klk said:I know I am probably just not understanding the question but....What is quadratic function whose vertex is (1,5) and y-intercept is -3 ? How do I solve this?
The quadratic function whose vertex is at (h,k) is
y = A*(x-h) + k
Solve for A knowing the x-intercept.
Subhotosh Khan said:klk said:I know I am probably just not understanding the question but....What is quadratic function whose vertex is (1,5) and y-intercept is -3 ? How do I solve this?
The quadratic function whose vertex is at (h,k) is
y = A*(x-h)[sup:3bz3du3a]2[/sup:3bz3du3a] + k
Solve for A knowing the x-intercept.
slight error, noted above...
klk said:I know I am probably just not understanding the question but....What is quadratic function whose vertex is (1,5) and y-intercept is -3 ? How do I solve this?
As you've been told, the equation of a quadratic function with vertex (h, k) is
y = a(x - h)^2 + k
You know the vertex is (1, 5). Substitute 1 for h and 5 for k:
y = a(x - 1)^2 + 5
You are also told that the y-intercept is -3. The y-intercept is a point on the y-axis...and EVERY point on the y-axis has an x-coordinate of 0. If the y-intercept is -3, then the point (0, -3) is ON the graph.
You can substitute 0 for x, and -3 for y in
y = a(x - 1)I^2 + 5
-3 = a(0 - 1)^2 + 5
-3 = a(-1)^2 + 5
Solve that for "a" and you can complete the equation of the quadratic function.
-3 = a(0 - 1)^2 + 5
-3 = a + 5
Solve that for a