How do you find the important points to graph #y=-2x-3#?

Question

2487 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2015-11-10T10:51:30

Find the points at which the line crosses the x and y axes.

#x# intercept
When a point is on the #x# axis, we know its #y# value is 0. This means we can make the equation equal to 0 to find #x#.

#0 = -2x -3#

#3 = -2x# (add 3 to both sides)

#3/2 = -x# (divide by 2 on both sides)

#-3/2 = x# (times both sides by -1)

This means #x = -3/2# or #x = -1.5# So our #x# intercept is at the coordinate #(-1.5, 0)#

#y# intercept
On the #y# axis we know the #x# value is equal to 0, so we can substitute this into the equation to find the #y# value.

#y = -2(0) - 3#

#y = -3# (remove anything multiplied by 0)

So we now know our #y# intercept is at #(0,-3)#

So the important points are #(-1.5, 0)# and #(0, -3)#