Question

Which equation represents a linear function?

Answer 1

Answer:

y - 5 = x - 20

Step-by-step explanation:

The equation of a linear function in

slope-intercept form: $y=mx+b$

point-slope form: $y-y_1=m(x-x_1)$

standard form: $Ax+By=C$

general form: $Ax+By+C=0$

1.

y(x - 1) = 9

xy - y = 9   NO

2.

y - 5 = x(-x + 2)

y - 5 = -x² + 2x    NO

3.

y(y - 1) = x + 25

y² - y = x + 25    NO

4.

y - 5 = x - 20

y - 5 = 1(x - 20)    YES   (it's a point-slope form)