Question

Write in slope-intercept form an equation of the line that passes through the given points. When the points are, (-1,4) and (3,8)...... please help.

Answer 1

I find it easiest to start with the 2-point form of the equation of a line.
  y = (y₂-y₁)/(x₂-x₁)*(x-x₁) +y₁
where the given points are (x₁, y₁) and (x₂, y₂).

Substituting the given numbers, you have
  y = (8 -4)/(3 -(-1))*(x -(-1)) +4
  y = 4/4(x +1) +4
  y = x +5

The desired slope-intercept form of the equation for the line is ...
  y = x + 5

Answer 2

Slope is change in y over change in x, which is 1.  

The equation is y=mx+b, but we only know the slope. We need the y-intercept now.

y=x+b (1x can be written as x)

b=5.

The equation is y=x+5.