# Find the image of a line

1. Mar 20, 2013

### 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 cant figure out gow to get the image of the line
the back says the answer should be 9y1-4y2=6 and ive spent over a hour on this and im not seeing it

2. Mar 20, 2013

### Dick

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

3. Mar 20, 2013

### 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

4. Mar 20, 2013

### Dick

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

5. Mar 20, 2013

### Octavius1287

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

x2=-2y1+y2

6. Mar 20, 2013

### Dick

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

7. Mar 20, 2013

### Octavius1287

oooh ok thanks. why cant the book just say that!