How about -x^2+ 9? May you please explain why and inform me of any postulate etc?
2007-10-15 04:27:57 · 4 answers · asked by GLAYS S 2 in Science & Mathematics ➔ Mathematics
Why ccould the answer be (-x-3)(x-3)?
2007-10-15 07:28:08 · update #1
Why couldn't* for the last detail add
2007-10-15 07:32:09 · update #2
- (x - 3) (x + 3) [Kemmy].
If you multiply through by -1,
you get:
(x + 3) (x - 3).
The same!
2007-10-15 04:43:01 · answer #1 · answered by BB 7 · 0⤊ 0⤋
You can factor out a -1 from the first and you will get
(-1)(x^2 + 9)
but there is not much more you can do with that. With the second, you get
(-1) (x^2 - 9)
x^2 - 9 factors to
(x + 3)(x - 3), so that gives you
(-1)(x + 3)(x - 3), this can by simplified slightly to
(x + 3)(3 - x), but that is a matter of taste.
You were using the distributive law to factor out the -1
HTH
Charles
2007-10-15 11:35:36 · answer #2 · answered by Charles 6 · 0⤊ 0⤋
- x^2 - 9 = 0
- (x - 3) (x + 3) = 0
- x + 3 = 0, - x = - 3, x = 3
x + 3 = 0, x = - 3
Answer: x can either be 3 or - 3
Proof (x is 3):
- 3^2 - 9 = 0
9 - 9 = 0
Proof (x is - 3):
- (- 3^2) - 9 = 0
3^2 - 9 = 0
9 - 9 = 0
2007-10-15 11:44:20 · answer #3 · answered by Jun Agruda 7 · 2⤊ 0⤋
-x^2 -9 = - (x^2 + 9)
-x^2+ 9 = -(x^2 - 9) = -(x-3)(x+3)
2007-10-15 11:31:58 · answer #4 · answered by Kemmy 6 · 0⤊ 0⤋