Question

I'm going crazy over her. I've been to Khan academy and the website where I do my math but I can not for the life of me graph a quadratic. Can someone explain to me how to graph
y=-4(x-6)^2+2

Answer 1

I use Wolframalpha ----> http://www.wolframalpha.com/input/?i=+y%3D-4%28x-6%29%5E2%2B2 <----

Answer 2

i just make a U, or an upside down U

Answer 3

LOL! @amistre64

Answer 4

That website is great. Thank you for telling me about it. But I also need to know how to solve it without a website.

Answer 5

Step 1: find the vertex
If the equation is\[y=a(x-h)^2+k\]
The vertex is at (h,k)

Answer 6

@Akjankins No problem!

Answer 7

@DDCamp Alright, I'm following.

Answer 8

y=-4(x-6)^2+2
^
first term is negative, this models -x^2
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let x = 0 to find the point it hits the y axis: y=-4(-6)^2+2
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y=-4(x-6)^2+2
^ ^^
these represent the vertex
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let y = 0 to define the points of intersection with the x axis

0 =-4(x-6)^2+2 , solve for x

Answer 9

Step 2: Find the direction (pretty easy)
If a is positive, graph is U shaped. if a is negative, graph is upside down U shaped.

Answer 10

Step 3: Plot some points
To get the best idea for the shape of the graph, plot points around the vertex (So if the vertex is at x=6, make a table for x= 4, 5, 7, & 8, then plot those points.)

Answer 11

Thanks all of you.