The question asks me to determine the intersection 3x-y=11 and 3x2-y2 = 47 This is the given answer.
3x2 -9x2 +66x-121-47=0
-6x2+ 66x - 168= 0
x2 -11x +28 = 0
..... and so on
The problem I'm having is in line 3. I'm not sure where the '66x' came from?
I can see that 3x squared = 9x2 and I see that -11 squared = 121, however I don't know where the (2 x 11 x 3)x came from :S
Also in the given answer for the question it says that instead of 121 it's -121.. im so confused.
Yes thank you very much, I see how it was done now, however I highly doubt I will ever be able to do it myself on a test. I had to stare at this for a while and I'm still having trouble understanding it completely.
Thank you though, I've definitely come as close to understanding it as I probably ever will.