Solving Inequalities Watch
However in the book the sign is the other way round which I know is correct but why are they flipping the sign?
10 > 7
Multiply/Divide both by -1 and you get -10 and -7
I assume that you are happy that
-10 < -7
anyone know what I'm doing wrong
Now of course you don't need to think of this every time you work through an inequality, but it helps to understand why the sign sometimes changes and serves as a sort of 'proof' if you will.
In your case, multiplying by -1 is equivalent to taking of both sides where As you well know decreases, hence the change of sign.