What is the y intercept for a line with point (9,-5) slope -1?

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Answer 1 · 2015-09-29T22:22:41

The y intercept = 4

The general equation for a straight line is:

#y=mx+c#

#m# is the gradient

#c# is the intercept which is the point at #x=0# where the line cuts the #y# axis.

From the co-ordinates given we can say that:

#x=9#

#y=-5#

Putting these values into the general equation gives:

#-5=(-1xx9)+c#

#9-5=c#

#c=4#

Which is the #y# intercept.

This means the equation of the line is:

#y=-x+4#

It looks like this:

graph{y=-x+4 [-2.44, 7.56, -0.32, 4.68]}

You can see how the line cuts the y axis at #y=4#