I am confused on the notation used when writing down the solution of x and y in quadratic equations.
For example in $x^2+2x-15=0$, do I write :
$x=-5$ AND $x=3$
or is it
$x=-5$ OR $x=3$
which is it and why? I thought that because x can only equal one of the values when you substitute it in so it would be OR, however there are sometimes 2 roots of a quadratic so is it more correct to use AND? What about for the value of $y$, is it the same?
Thanks in advance
Best Answer
It depends on the context. Consider these two examples:
The solutions to $x^2+2x-15=0$ are $x=-5$ and $x=3$.
If $x^2+2x-15=0$ then $x=-5$ or $x=3$.
In both cases, it would be wrong to use 'or' in stead of 'and' or 'and' in stead of 'or'.