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Question 798369: On what interval is the function f(x)=x^2-2x-9 increasing?
Answer by nerdybill(7384)   (Show Source):
You can put this solution on YOUR website! On what interval is the function f(x)=x^2-2x-9 increasing?
we know that
f(x)=x^2-2x-9
is a "quadratic" (parabola)
we also know that it opens upwards (POSITIVE leading coefficient).
So, the "increasing" portion is the right side of the vertex.
.
Now we need the axis of symmetry or x-coordinate:
x = -b/(2a)
x = -(-2)/(2*1)
x = 2/(2)
x = 1
.
Therefore, the interval where the function is increasing (in interval notation):
(1, +oo)
where oo stands for infinity
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