how do you solve 1/x=1/t + 1/r ??

and -4<2 (x-3)< 8

Printable View

- Apr 2nd 2006, 10:23 AMdyr[SOLVED] algebra
how do you solve 1/x=1/t + 1/r ??

and -4<2 (x-3)< 8 - Apr 2nd 2006, 11:42 AMearbothQuote:

Originally Posted by**dyr**

to 1.: You need a common denominator (which is here r*t):

$\displaystyle \frac{1}{x}=\frac{r+t}{r \cdot t}\ \Rightarrow \ x=\frac{r \cdot t}{r+t}$

to 2.: Split the inequalities into two single inequalities:

$\displaystyle -4<2 (x-3)< 8\ \Leftrightarrow \ -4<2(x-3)\ \ \wedge \ \ 2(x-3)<8$

$\displaystyle 1 < x\ \wedge \ x < 7\ \Leftrightarrow \ 1<x<7$

Greetings

EB