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Maths Exercices

Equations of straight lines

When working with straight lines, there are often many ways to arrive at an equation. Let's see:

Slope Intercept Form
(if you know the slope and where the
line crosses the y-axis, use this form)

y = mx + b

m = slope
b = y-intercept
 (where line crosses the y-axis.)

Point Slope Form
(if you know a point and the slope,
 use this form)

m = slope
= any point on the line.


Find the equation of the line that goes through two points P(x 1,x2) and Q(y1,y2)
Firts find the slope using
and then use the formula:

Write the slope-intercept form of the equation of the line with the slope 2 that contains the point (-4,-5).
Use the slope-intercept form to find b:

Then y=2x+3

Write the equation of the line that contains point P(-8,5) and has slope m= -5

Solution: y= x+