Questions: Find the coordinates of the vertex, by hand, of the graph of the function. Tell whether the vertex is a maximum or a minimum.
y=2x^2+4x+7
Transcript text: Find the coordinates of the vertex, by hand, of the graph of the function. Tell whether the vertex is a maximum or a minimum.
\[
y=2 x^{2}+4 x+7
\]
Solution
Solution Steps
To find the vertex of a quadratic function in the form \( y = ax^2 + bx + c \), we use the vertex formula \( x = -\frac{b}{2a} \). Once we have the x-coordinate, we substitute it back into the function to find the y-coordinate. The vertex will be a minimum if \( a > 0 \) and a maximum if \( a < 0 \).
Step 1: Find the x-coordinate of the Vertex
To find the x-coordinate of the vertex for the quadratic function \( y = 2x^2 + 4x + 7 \), we use the formula:
\[
x = -\frac{b}{2a}
\]
Substituting \( a = 2 \) and \( b = 4 \):
\[
x = -\frac{4}{2 \cdot 2} = -\frac{4}{4} = -1
\]
Step 2: Find the y-coordinate of the Vertex
Next, we substitute \( x = -1 \) back into the function to find the y-coordinate:
\[
y = 2(-1)^2 + 4(-1) + 7
\]
Calculating this gives:
\[
y = 2(1) - 4 + 7 = 2 - 4 + 7 = 5
\]
Step 3: Determine if the Vertex is a Maximum or Minimum
Since the coefficient \( a = 2 \) is greater than 0, the vertex represents a minimum point.
Final Answer
The coordinates of the vertex are \( (-1, 5) \) and it is a minimum. Thus, the answer is:
\[
\boxed{(-1, 5) \text{ ; minimum}}
\]