• Jan 29th 2009, 05:57 PM
algebra_fan
a does not = b

a(x+b)=bx-c

and my test review says the answer is:

ab+c/ b-a

but I keep getting -ab-c/a-b

so my negative signs are the complete opposite of theirs, and I have no idea why. Am I doing it right? Is there a problem with their answer?

here's my work :

a(x+b)=bx-c

ax+ab=bx-c

ax-bx= -ab-c

x(a-b)= -ab-c

x= -ab-c/ a-b

Can anyone confirm my work or show a flaw in it? Thank you so much!
• Jan 29th 2009, 06:03 PM
Rapha
Hi dude.

Quote:

Originally Posted by algebra_fan
a does not = b

a(x+b)=bx-c

and my test review says the answer is:

ab+c/ b-a

but I keep getting -ab-c/a-b

so my negative signs are the complete opposite of theirs, and I have no idea why. Am I doing it right? Is there a problem with their answer?

here's my work :

a(x+b)=bx-c

ax+ab=bx-c

ax-bx= -ab-c

x(a-b)= -ab-c

x= (-ab-c)/ (a-b)

Can anyone confirm my work or show a flaw in it? Thank you so much!

This is correct, the text book's solution is correct too,

I think it says: x = (ab+c)/ (b-a)

Considering your solution [ It is a-b = -(b-a) ]

$x= \frac{-ab-c}{a-b}$

$= \frac{-(ab+c)}{-(b-a)} = \frac{ab+c}{b-a}$

Whatever, you did a good job!

Regards,
Rapha