On Wed, 16 Apr 2008 henrysun909@[EMAIL PROTECTED]
wrote:
> In the book, Algebra Demystified," the author presents this problem as
> the part of the final book review (problem #57):
>
> 4x(x-3) - 5(3x-6) = (2x - 3)2
>
I think you screwed up posting in a plain text news group with word
processing formating or using special characters.
What I see is (2x - 3)2 which of course equals 2(2x - 3)
Here's what I think you mean
4x(x - 3) - 5(3x - 6) = (2n - 3)^2
In these newsgroups, the standard notation for a to the n-th power is
a^n.
Thus a^2 and not a2 = 2a.
> The author's answer is 7/5, which is correct.
>
> However, when I solve the problem I get something entirely different,
> namely:
>
> (4x2 - 12x) - (15x - 30) = 4x2 - 12x + 9
No. You don't mean 4x2 = 2 * 4x = 8x, you mean 4x^2.
4x^2 - 12x - (15x - 30) = 4x^2 - 12x + 9
Immediately
-(15x - 30) = 9
-15x + 30 = 9
23 = 15x
> 4x2 - 27x + 30 = 4x2 - 12x + 9
> -27x + 30 = -12x + 9
> 21 = 25x
>
> which is obviously different from the author's solution.
>
> Can someone please show me where I screwed up the calculation?
>
> Thanks in advance.
>
> Henrysun909
>
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