Question

What is the equation of the line that passes through the point (4,-7) and has a slope of -3

Answer 1

Answer: y= -3x +5

Explanation:

Slope: y= mx+ b

m being the slope

b being the y intercept

You're given the slope, so you substitute m for -3

y=mx+b

y = -3x + b

You have the coordinates (4, -7) which you can substitute (the line passes through that point.)

-7 = -3(4) + b

-7 = -12 + b

+12 +12

5= b

y= -3x + b

Check:

-7 = -3(4) + 5

-7 = -12 + 5

-7 = -7

Answer 2

Answer: y=-3x+5

Explanation:

1) List in a y = mx + b

y = -3x+b

2) Next fill in x and y with the points given

-7 = -3(4) + b

3) Solve

-7 = -3(4) + b

-7 = -12 + b

5 = b

4) Apply b to the y =mx + b

y=-3x+5