28. The graph of a quadratic function is shown on the grid. -2
-1
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N
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S
8
9
1
2
النا
4
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Which function is best represented by this graph?

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.

so what is the problem what are they asking you to solve

step-by-step explanation:

so what is the problem what are they asking you to solve