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

Results 1 to 4 of 4

- Feb 2nd 2010, 01:45 PM #1

- Joined
- Feb 2010
- Posts
- 1

- Feb 2nd 2010, 02:05 PM #2

- Joined
- Dec 2009
- Posts
- 3,120
- Thanks
- 4

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 PM #3

- Feb 3rd 2010, 05:33 AM #4

- Joined
- Apr 2005
- Posts
- 19,587
- Thanks
- 2935