Question

Select the correct answer.

What is the equation of a line that passes through (7.8) and has a slope of -3?
A.
y=-3x + 29
B.
c.
D.
y = 3x + 13
y = (1)/(3)x-29
y = -(1)/(3)x-13
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2019 EdmontumAllah

Answer 1

A

Explanation:

The equation of a line in slope- intercept form is

y = mx + c ( m is the slope and c the y- intercept )

here m = - 3, so

y = - 3x + c ← is the partial equation of the line

To find c substitute (7, 8) into the partial equation

8 = - 21 + c ⇒ c = 8 + 21 = 29

y = - 3x + 29 → A

Answer 2

A. y=-3x + 29

Explanation:

The slope shows up in the equation as the coefficient of x. Only answer choice A has an x-coefficient of -3. It also happens to describe a line that goes through (7, 8).

y = -3x +29

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Check

y = -3·7 +29 = -21 +29 = 8 . . . . as required