Question

Which of the following is an equation that has a slope of 5 and passes through the point (4, 8)?

Answer 1

y = mx + b
slope(m) = 5
(4,8)...x = 4 and y = 8
now we sub, we r looking for b, the y intercept
8 = 5(4) + b
8 = 20 + b
8 - 20 = b
-12 = b

equation is : y = 5x - 12...but we need it in standard form...
y = 5x - 12...subtract 5x from both sides
-5x + y = -12 ...multiply by -1 to make x positive
5x - y = 12 <== standard form

Answer 2

The general equation of the line is;
y=mx+c
y=5x+c
Replacing for x and y using point (4,8)
8=5(4)+c
8=20+c
c=8-20
c=-12
y=5x-12