SOLUTION: I am trying to graph y=-x^2 -8x +9, I am not sure how to solve and graph

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Question 153191: I am trying to graph y=-x^2 -8x +9, I am not sure how to solve and graph
Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!

Table of Contents:


Jump to Table
Jump to Graph


In order to graph , we need to plot some points.


Let's find y when
(Note: you can start with any x-value):


Start with the given equation.


Plug in .


Square to get .


Multiply and to get .


Multiply and to get .


Combine like terms.


So when , then .


So we have the point .


----------------------------------------------------


Let's find y when :


Start with the given equation.


Plug in .


Square to get .


Multiply and to get .


Multiply and to get .


Combine like terms.


So when , then .


So we have the point .


----------------------------------------------------


Let's find y when :


Start with the given equation.


Plug in .


Square to get .


Multiply and to get .


Multiply and to get .


Combine like terms.


So when , then .


So we have the point .


----------------------------------------------------


Let's find y when :


Start with the given equation.


Plug in .


Square to get .


Multiply and to get .


Multiply and to get .


Combine like terms.


So when , then .


So we have the point .


----------------------------------------------------


Let's find y when :


Start with the given equation.


Plug in .


Square to get .


Multiply and to get .


Multiply and to get .


Combine like terms.


So when , then .


So we have the point .


----------------------------------------------------


Let's find y when :


Start with the given equation.


Plug in .


Square to get .


Multiply and to get .


Multiply and to get .


Combine like terms.


So when , then .


So we have the point .


----------------------------------------------------


Let's find y when :


Start with the given equation.


Plug in .


Square to get .


Multiply and to get .


Multiply and to get .


Combine like terms.


So when , then .


So we have the point .


----------------------------------------------------


Let's find y when :


Start with the given equation.


Plug in .


Square to get .


Multiply and to get .


Multiply and to get .


Combine like terms.


So when , then .


So we have the point .


----------------------------------------------------


Let's find y when :


Start with the given equation.


Plug in .


Square to get .


Multiply and to get .


Multiply and to get .


Combine like terms.


So when , then .


So we have the point .


----------------------------------------------------


Let's find y when :


Start with the given equation.


Plug in .


Square to get .


Multiply and to get .


Multiply and to get .


Combine like terms.


So when , then .


So we have the point .


----------------------------------------------------


Let's find y when :


Start with the given equation.


Plug in .


Square to get .


Multiply and to get .


Multiply and to get .


Combine like terms.


So when , then .


So we have the point .


----------------------------------------------------





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Now let's make a table of the values we just found.


Table of Values:





xy
-90


-89


-716


-621


-524


-425


-324


-221


-116


09


10

Now let's plot the points:







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Graph:


Now draw a curve through all of the points to graph :


Graph of
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