(1/a)=(1/b)+(1/c) Find the value of a if b=3 and c=7 It has been year since I did any math, Could I please get an explanation of how to solve this problem. Thank you very much.
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Originally Posted by rms390 (1/a)=(1/b)+(1/c) Find the value of a if b=3 and c=7 It has been year since I did any math, Could I please get an explanation of how to solve this problem. Thank you very much. $\displaystyle \displaystyle \frac {1}{a}= \frac {1}{b}+ \frac {1}{c}$ $\displaystyle \displaystyle \frac {1}{a}= \frac {1}{3}+ \frac {1}{7}$ multiply all by (21a ) $\displaystyle \displaystyle 21= 7a + 3a \Rightarrow 10a=21 \Rightarrow a=\frac {21}{10} = 2.1$
Originally Posted by rms390 (1/a)=(1/b)+(1/c) Find the value of a if b=3 and c=7 It has been year since I did any math, Could I please get an explanation of how to solve this problem. Thank you very much. Or... $\displaystyle \displaystyle\frac{1}{a}=\frac{1}{b}+\frac{1}{c}=\ frac{c}{c}\ \frac{1}{b}+\frac{b}{b}\ \frac{1}{c}=\frac{c+b}{cb}$ $\displaystyle \Rightarrow\displaystyle\ a=\frac{cb}{c+b}$ for various values of $\displaystyle c$ and $\displaystyle b.$
thank you very much
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