It has been a great many years since I did any algebra, now my son hits me with this:-

x squared + 2x = y find x and y

x squared + 2x = 48 find x

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- Feb 2nd 2010, 01:45 PMdivorce3My Son
It has been a great many years since I did any algebra, now my son hits me with this:-

x squared + 2x = y find x and y

x squared + 2x = 48 find x - Feb 2nd 2010, 02:05 PMArchie Meade
For the second one, you could write

The factors of 48 that differ by 2 are 6 and 8, so x=6

or -6 and -8 so x=-8 as that is 2 less than -6.

Or

We are looking for the factors of -48 that add to give 2,

these are -6 and 8, since

Two values multiplied give zero means x-6=0 or x+8=0,

so x=6 or -8.

For the first one, you need more information, because you can take any x,

square it and add 2x and call the answer y. - Feb 2nd 2010, 02:17 PMpickslides
- Feb 3rd 2010, 05:33 AMHallsofIvy
How is that different from just saying for any value of x?