Question the-gr

1.1 Linear Functions - Graphs in slope-intercept, point-slope, standard form
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The graph of the function f is a line in the xy-plane. If the line has slope three-fourths and f of 0, equals 3, which of the following defines f?

A.

f of x equals, three fourths x, minus 3

B.

f of x equals, three fourths x, plus 3

C.

f of x equals, 4 x, minus 3

D.

f of x equals, 4 x, plus 3

The graph of the function f is a line in the xy -plane. If the line

Easy-difficulty · SAT Math · Linear Functions — Graphs in slope-intercept, point-slope, standard form. Read the question above, select your answer, and check the full explanation below to understand exactly why the correct choice works.

Answer explanation

Choice B is correct. The equation for the function f in the xy-plane can be represented by f of x equals, m x plus b, where m is the slope and b is the y-coordinate of the y-intercept. Since it’s given that the line has a slope of three fourths, it follows that m equals three fourths in f of x equals, m x plus b, which yields y equals, three fourths x, plus b. It’s given that f of 0 equals 3. This implies that the graph of the function f in the xy-plane passes through the point with coordinates 0 comma 3. Thus, the y-coordinate of the y-intercept of the graph is 3, so b equals 3 in f of x equals, three fourths x, plus b, which yields f of x equals, three fourths x, plus 3. Therefore, the equation f of x equals, three fourths x, plus 3 defines the function f.

Choice A is incorrect and may result from a sign error for the y-intercept. Choice C is incorrect and may result from using the denominator of the given slope as m in f of x equals, m x plus b, in addition to a sign error for the y-intercept. Choice D is incorrect and may result from using the denominator of the given slope as m in f of x equals, m x plus b.