Since the parabola opens downwards, you said that, there is a maximum point
That point is called the vertex, you had it incorrectly at (2,12), should have been
(2, 4)
you should precede your calculation with statements, such as
the x of the vertex = -b/(2a) = -4/(2(-1)) = 2
the y of the vertex = -x^2 + 4x = -(2^2) + 4(2) = -4 + 8 = 4
check: www.wolframalpha.com/input/?i=f(x)+%3D+-x%5E2+%2B+4x
Could someone check my work? I want to make sure I got the answer correct because I've never done a problem like this one. Thanks.
Determine whether the function f(x) = -x^2 + 4x has a minimum or maximun value.
a= -1
b =4
-1< 0 = parabola down
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x = -4 / 2(-1) = 2
y = -2^2 + 4(2) = 12
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Maximum value = (2,12)
2 answers
Wouldn't (-2)^2 equal 4?
5 answers