Question

Se a$<var>Se\ a^{-1}\ +b^{-1}=\ c^{-1}\ ;\ a=\frac{-1}{2}\ e \ b=\frac{1}{3}\ ,\ então \ c \ vale:</var>$

Answer 1

$<var>a^{-1}= \frac{1}{a} e\ b^{-1}= \frac{1}{b} a=-1/2 \ logo \ a^{-1}=-2\\ b=1/3 \ logo \ b^{-1}=3\\ {a}^-1 +{b}^-1= {c}^-1\\ -2 +3={c}^-1\\ 1={c}^-1\\ c=1</var>$

Answer 2

$\\ a^{- 1} + b^{- 1} = c^{- 1} \\\\ \left ( \frac{- 1}{2} \right )^{- 1} + \left ( \frac{1}{3} \right )^{- 1} = c^{- 1} \\\\ \left (\frac{1}{c} \right )^{+ 1} = \left ( \frac{2}{- 1} \right )^{+ 1} + \left ( \frac{3}{1} \right )^{+ 1} \\\\ \frac{1}{c} = - 2 + 3 \\\\ \frac{1}{c} = 1 \\ \boxed{c = 1}$