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Factorization?
can someone show me how (2x-4)^2=3x^3-6x is x=2, x=8??
6 Answers
- ?Lv 72 months ago
x=2 or x=8 are not the solutions of the given equation.
(2x-4)^2=3x^3-6x=>
4x^2-16x+16=3x^3-6x=>
3x^3-4x^2+10x-16=0=>
The only real solution of the equation is
x=1.493126 approximately.
You may check that if
f(x)=(2x-4)^2-3x^3+6x=0, then
f(2)=/=0
&
f(8)=/=0
- billrussell42Lv 72 months ago
x = 2 or 8 are not solutions, see below.
(2x – 4)² = 3x³ – 6x
4x² – 16x + 16 = 3x³ – 6x
3x³ – 4x² + 16x – 6x – 16 = 0
3x³ – 4x² + 10x – 16 = 0
now to factor... which is complicated. A graphical solution is easy...
and it has only one root, x = 1.493 about
(2x – 4)² = 3x³ – 6x
does x = 2 or 8 work?
(2•2 – 4)² = 3•2³ – 6•2
0 = 16 – 12 NO
(2•8 – 4)² = 3•8³ – 6•8
12² = 1536 – 48
144 = 1488 NO
- ?Lv 72 months ago
You can try "good guesses".
Or, expand and rewrite as a poly. Then try to find the roots of the poly:
Try RRT, or "the formula"...
Here, the solutions are NOT 2 & 8 btw.
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- llafferLv 72 months ago
(2x - 4)² = 3x³ - 6x
I don't see how this has to do anything with factoring, but x = 2 or 8 are not solutions to this equation. Testing them:
(2 * 2 - 4)² = 3 * 2³ - 6 * 2 and (2 * 8 - 4)² = 3 * 8³ - 6 * 8
(4 - 4)² = 3 * 8 - 12 and (16 - 4)² = 3 * 512 - 48
0² = 24 - 12 and 12² = 1536 - 48
0 = 12 and 144 = 1488
FALSE and FALSE
Neither are solutions.
Looking at a graph, there is only one real (irrational) solution and the other two are complex.