SOLUTION: Find the greatest value of each function.
f:x -x^2-3x
Please demonstrate with steps.
I need lots of help on this.
My teacher just introduced me to quadratic funtions and I d
Question 1047916: Find the greatest value of each function.
f:x -x^2-3x
Please demonstrate with steps.
I need lots of help on this.
My teacher just introduced me to quadratic funtions and I don't understand.
Thank you very much.
God bless you. Found 2 solutions by stanbon, AnlytcPhil:Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website! Find the greatest value of each function.
f(x) = -x^2-3x
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The maximum value of y occurs when x = -b/(2a)
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In your problem a = -1, b = -3
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Max occurs when x = 3/(2*-1) = -3/2
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The maximum value of y = f(-3/2) = -(-3/2)^2 - 3(-3/2) = -(9/4) + (18/4)
= (9/4)
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Cheers,
Stan H.
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Watch this video to learn about quadratic functions.
https://www.youtube.com/watch?v=QJU-nfaTSto
y = -x^2-3x
compare to y = ax^2+bx+c
a=-1, b=-3, c=0
It opens downward because a is negative.
The greatest value is found at the vertex.
the x-coordinate of the vertex is -b/(2a)
-(-3)/(2*-1) = -3/2
Find the y-coordinate on the vertex by substituting
y = -x^2-3x
y = -(-3/2)^2-3(-3/2)
y = -9/4+9/2
y = -9/4+18/4
y = 9/4
So the vertex is the point (-3/2, 9/4).
And the y-value of the vertex is the greatest value of
the function if the graph opens downward, and the least
value if the graph opens upward.
So the greatest value is 9/4 or 2.25.
Here's the graph with the vertex at the top.
Edwin
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