SOLUTION: this is one question with different parts Find the vertex, line of symmetry, maximum or minimum value of the quadratic function, and graph the function. f(x)=-2x^2+2x+3 x-coord

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Question 176168: this is one question with different parts
Find the vertex, line of symmetry, maximum or minimum value of the quadratic function, and graph the function.
f(x)=-2x^2+2x+3
x-coordinate of vertex
y-coordinate of vertex
equation of line of symmetry
max/min value of f(x)
The value of f(1/2)=7/2 is min or max
Please help I have no idea what I am doing thank you

Found 2 solutions by solver91311, MathLover1:
Answer by solver91311(24713)   (Show Source): You can put this solution on YOUR website!
If you have a function , you have a parabola with vertex at the point

So, calculate to get the x-coordinate of the vertex. Then substitute that x-coordinate value into the function and calculate the y-coordinate of the vertex.

The axis of symmetry is the vertical line where v is equal to the x-coordinate of the vertex, or .

If the lead coefficient, in other words the coefficient on the term is positive, then the parabola is concave up and the vertex is a minimum. If the lead coefficient is negative, then the parabola is concave down and the vertex is a maximum.

To graph the function, first plot the vertex point. Then add a convenient value to the x-coordinate and recalculate the value of the function to get another point on the graph. Because of symmetry, you will also have the same value of the function when you subtract the same amount from the x-coordinate. Perform this process 3 or 4 times to get a set of points and then draw a smooth curve through the plotted points.

Your graph should look like this:


Answer by MathLover1(20850)   (Show Source): You can put this solution on YOUR website!
1. Quadratic into Vertex Form
Solved by pluggable solver: Completing the Square to Get a Quadratic into Vertex Form


Start with the given equation



Subtract from both sides



Factor out the leading coefficient



Take half of the x coefficient to get (ie ).


Now square to get (ie )





Now add and subtract this value inside the parenthesis. Doing both the addition and subtraction of does not change the equation




Now factor to get



Distribute



Multiply



Now add to both sides to isolate y



Combine like terms




Now the quadratic is in vertex form where , , and . Remember (h,k) is the vertex and "a" is the stretch/compression factor.




Check:


Notice if we graph the original equation we get:


Graph of . Notice how the vertex is (,).



Notice if we graph the final equation we get:


Graph of . Notice how the vertex is also (,).



So if these two equations were graphed on the same coordinate plane, one would overlap another perfectly. So this visually verifies our answer.






Solved by pluggable solver: Min/Max of a Quadratic Function
The min/max of a quadratic equation is always at a point where its first differential is zero. This means that in our case, the value of at which the given equation has a maxima/minima must satisfy the following equation:
=>

This point is a minima if value of coefficient of x2 is positive and vice versa. For our function the point x=0.5 is a The graph of the equation is :

Alternate method


In this method, we will use the perfect square method.


Step one:
Make the coefficient of positive by multiplying it by in case.
Maxima / Minima is decided from the sign of 'a'.
If 'a' is positive then we have Minima and for 'a'negative we have Maxima.

Step two:
Now make the perfect square with the same and coefficient.


Maxima / Minima lies at the point where this squared term is equal to zero.

Hence,
=>

This point is a minima if value of coefficient of x2 is positive and vice versa. For our function the point x=0.5 is a .

For more on this topic, refer to Min/Max of a Quadratic equation.


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