Answer:
Focus of a Parabola. A parabola is set of all points in a plane which are an equal distance away from a given point and given line. The point is called the focus of the parabola and the line is called the directrix. The focus lies on the axis of symmetry of the parabola.
Step-by-step explanation:

A linear function has 1 as the highest power of the variable.
A. f(x) = 2 - 7x
here, the highest power of the variable x is 1.
Hence it is a LINEAR function.
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B. f(x) = 2 + x + x^2
here, the highest power of the variable x is 2.
Hence it is NOT a linear function.
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here, the highest power of the variable x is 1/2.
Hence it is NOT a linear function.
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24+15+11=50, the total number of times the markers were chosen.
Since 11 of these 50 tries resulted in a red and blue marker, the probability is 11/50. This is equal to 0.22 or 22%.