Question

Calculati:
${2}^{ - 1} + {2}^{ - 2} + {2}^{ - 3}$
​

Answer 1

${x}^{ - y} = \frac{1}{ {x}^{y} } \\ \\ \frac{1}{2} + \frac{1}{4} + \frac{1}{8} \\ \frac{4 + 2 + 1}{8 } = \frac{7}{8}$

Answer 2

Explicație pas cu pas:

$\frac{1}{2} + (\frac{1}{2}) {}^{2} + (\frac{1}{2} ) {}^{3} = \frac{1}{2} + \frac{1}{4} + \frac{1}{8} \\ aducem \: la \: acelasi \: numitor \: \\ \frac{4 + 2 + 1}{8} = \frac{7}{8}$