K kdmt New member Joined Jun 22, 2007 Messages 2 Jun 22, 2007 #1 I am stuck on this equation because my algebra skills are not fresh what does this simplify into ((1/-r)-(1/r)) what i did was i found the lcd and i ended up with 2r but the solution in front of me says that it simplifies to -2/r
I am stuck on this equation because my algebra skills are not fresh what does this simplify into ((1/-r)-(1/r)) what i did was i found the lcd and i ended up with 2r but the solution in front of me says that it simplifies to -2/r
G galactus Super Moderator Staff member Joined Sep 28, 2005 Messages 7,203 Jun 22, 2007 #2 \(\displaystyle \L\\\frac{a}{b}+\frac{c}{d}=\frac{ad+bc}{bd}\) \(\displaystyle \L\\\frac{1}{-r}-\frac{1}{r}=\frac{r-(-r)}{-r^{2}}=\frac{2\not{r}}{-r^{\not{2}\text{1}}}=\frac{-2}{r}\) Does that help refresh your memory?.
\(\displaystyle \L\\\frac{a}{b}+\frac{c}{d}=\frac{ad+bc}{bd}\) \(\displaystyle \L\\\frac{1}{-r}-\frac{1}{r}=\frac{r-(-r)}{-r^{2}}=\frac{2\not{r}}{-r^{\not{2}\text{1}}}=\frac{-2}{r}\) Does that help refresh your memory?.
D Deleted member 4993 Guest Jun 22, 2007 #3 Another way to look at it: {1/-r} - {1/r} = -{1/r} - {1/r} = -{2/r}
