#Could someone explain this question?
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The first question is just asking for which points is the graph sloping downwards
Just looking visually at the graph it is 2<x<6
The second question is asking for which points does a horizontal line cuz the graph at only 1 point
Just looking visually that is k<0 or k>8 which u would write in set notation
For the last question we can let f(x) = ax³+bx²+cx+d but d=0 since it passes through the origin.
Also by factor theorem x and (x-6) are factors and moreover x=6 is a repeated root so (x-6)² is a factor
Hence f(x) = ax(x-6)²
Now we just need to find a
To find a we can substitute x=2 and f(x)=8 and get that 8 = 32a so a=1/4
Hence f(x) = x(x-6)²/4
f(x) = ax(x-6)²