Question 547006: So if I am given a graphy how do I find f(x)?
Please help me. I came up with 2 possilbe answers.
For example, f(2) is I find 2 on the x axis and find where it touches the graph and the f(x) is the y?
Or I find2 on the y axis and find where it touches the graph and the f(x) is the x?
Please plase please help me!
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! let's use an example
:
Say your told to graph f(x) = x^2 - 8x + 12
on a graph, f(x) = y, therefore rewrite the equation to
y = x^2 - 8x + 12
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:
When they say f(2), they mean find the value of y when x=2
When they say f(1), they mean find the value of y when x=1
:
find the points on the graph from +1 to + 7
f(1); x=1, replace x with 1 and find y
y = 1^2 - 8(1) + 12
y = 1 - 8 + 12
y = 5
The ordered x,y pair: 1, 5
:
do the same with f(3); x=3
y = 3^2 - 8(3) + 12
y = 9 - 24 + 12
y = -3
The ordered pair: 3, -3
We can make a table from doing this, doing the same for each value of x, find y
x | y
-------
1 | +5
2 | 0
3 | -3
4 | -4
5 | -3
6 | 0
7 | +5
choose the values for x, in the range that will give a meaningful graph, graph each point.
this equation should look like this
Look at the table and you can see that it agrees with the x,y value on the graph
Just remember that in graphing, f(x) just means y
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Did this help, any questions?
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