Paola C.
asked • 10/09/12I need help solving something
Like graphing quadratic equations
More
1 Expert Answer
Nicole C. answered • 10/09/12
Tutor
4.9
(167)
Increase confidence in math and science, chemistry, algebra II
y = x2 - 6x + 4
Use an equation that will help us find the x of our vertex point (x,y)
equation for x of your vertex = -b/2a
this equation
a = 1, b = -6, c = 4
vertex x = -(-6)/2(1) = 6/2 = 3
Take the x you just found and plug it back into original equation to find the y of your vertex
y = (3)2 - 6(3) + 4 = 9 - 18 + 4 = -5
Vertex is: (3,-5)
Now you can chose one or two points on either side of your vertex x and plug in to find a couple more points. Because vertex x = 3, lets use 2 and 4
y = (2)2 - 6(2) + 4 = 4 - 12 + 4 = -4 Point = (2,-4)
y = (4)2 - 6(4) + 4 = 16 - 24 + 4 = -4 Point = (2,-4)
If you need a couple more points then choose x to be 1 and 5.
Paola C.
I have the vertex down just I need to see how to graph them like I know how to graph the vertex just graphing from the axis symmetry?
Report
10/09/12
Nicole C.
Well the axis of symmetry will be straight up and down from your vertex any time you have a y = x2 type of equation.
You can either choose points like I did above on either side of your x of your vertex and create a table, then graph off of that table.
x: 1 2 3 4 5
y: -1 -4 -5 -4 -1
OR the general rule for graphing parabolas (starting at your vertex)
1) Right 1 and 1a up or down (up if a>0, down if a<0)
and Left 1 and 1a up or down
For your equation:
vertex: (3, -5)
Right 1 and 1(1) [a for this equation is 1], point: (4,-4)
Left 1 and 1(1), point: (2,-4)
2) Right 2 and 4a up or down (up if a>0, down if a<0)
and Left 2 and 4a up or down
For your equation:
vertex: (3, -5)
Right 2 and 4(1) [a for this equation is 1], point: (5,-1)
Left 2 and 4(1), point: (1,-1)
Report
10/09/12
Still looking for help? Get the right answer, fast.
Ask a question for free
Get a free answer to a quick problem.
Most questions answered within 4 hours.
OR
Find an Online Tutor Now
Choose an expert and meet online. No packages or subscriptions, pay only for the time you need.
Nicole C.
Can you please give me a specific problem?
10/09/12