Question
Question: How to graph a parabola \(y = \dfrac{1}{2}{(x - 3)^2} + 5\)?...
How to graph a parabola y=21(x−3)2+5?
Solution
In this question, we have an equation and we are supposed to plot a graph after solving it. This can be done when the correct points are found which will be only possible if a table of calculations is made and the values are calculated in order to solve the equation.
Complete step by step answer:
Construct a data table with input x and corresponding values for y:
This table will help immensely in understanding the End Behaviour of the given
Function: y=21(x−3)2+5
x | y=x2 | y=(x−3)2 | y=(21)(x−3)2 | y=(21)(x−3)2+5 |
---|---|---|---|---|
Col 1 | Col 2 | Col 3 | Col 4 | Col 5 |
-5 | 25 | 64 | 32.0 | 37.0 |
-4 | 16 | 49 | 24.5 | 29.5 |
-3 | 9 | 36 | 18.0 | 23.0 |
-2 | 4 | 25 | 12.5 | 17.5 |
-1 | 1 | 16 | 8.5 | 13.0 |
0 | 0 | 9 | 4.5 | 9.5 |
1 | 1 | 4 | 2.0 | 7.0 |
2 | 4 | 1 | 0.5 | 5.5 |
3 | 9 | 0 | 0.0 | 5.0 |
4 | 16 | 1 | 0.5 | 5.5 |
5 | 25 | 4 | 2.0 | 7.0 |
x:−5⩽x⩽5[ Col 1]
Draw graphs for y=x2,y=(x−3)2,y=(21)(x−3)2and finally y=(21)(x−3)2+5
Find Vertices, x-intercept and y-intercept, if any, for all the graphs.
Step 2
Graph: y=x2.....Parent Quadratic Function
Step 3
Graph: y=(x−3)2
Step 4
Graph: y=(21)(x−3)2
Step 5
Graph: y=(21)(x−3)2+5
And the last step is to view all the graphs together.
y=fx=(21)(x−3)2+5
General form: y=f(x)=a(x−h)2+k, Vertex: (a,h)
Graph opens up, as the x2 term is positive.
Parabolic curve is expanded outward, as 0<a<1
x=h and in our problem x=3 is the Axis of Symmetry
h=3 Indicates the Horizontal Shift
k=5 Indicates the Vertical Shift
Note: The graph of a quadratic function is a U-shaped curve called a parabola. The sign on the coefficient a of the quadratic function affects whether the graph opens up or down. If a<0, the graph makes a frown (opens down) and if a>0then the graph makes a smile (opens up).