Finding the Image of a Line for Beginners

[Octavius1287]

Im stuck on this, the book has no examples on this kind of problem (and its the first one) And i learn mostly from examples

Im on b) and i can't figure out gow to get the image of the line
the back says the answer should be 9y1-4y2=6 and I've spent over a hour on this and I am not seeing it

 

[Dick]

The first step is to find an expression for x1 and x2 in terms of y1 and y2.

 

[Octavius1287]

the book shows how to do that but only with 2 equation and putting them in matrix form then getting the inverse, i only have 1 equation. For this case its not explained and no example is given

 

[Dick]

the book shows how to do that but only with 2 equation and putting them in matrix form then getting the inverse, i only have 1 equation.

I mean do it with the equations defining the linear transformation. There are two of those.

 

[Octavius1287]

ok i got
x1=(3/2)y1-(1/2)y2

x2=-2y1+y2

 

[Dick]

ok i got
x1=(3/2)y1-(1/2)y2

x2=-2y1+y2

Great! Now substitute those into the line equation. That will give you the image of the line.

 

[Octavius1287]

oooh ok thanks. why can't the book just say that!