№ 4.50 Алгебра = № 9.31 Математика
Обчисліть:
1) $\left(\frac{1}{7}\right)^2; $
2) $\left(-\frac{4}{5}\right)^2;$
3) $\left(-\frac{1}{5}\right)^3;$
4) $\left(1\frac{1}{2}\right)^3.$
Розв'язок:
1) $\left(\frac{1}{7}\right)^2=\frac{1}{7}\cdot\frac{1}{7}=\frac{1}{49}; $
2) $\left(-\frac{4}{5}\right)^2=\left(-\frac{4}{5}\right)\cdot\left(-\frac{4}{5}\right)=\frac{16}{25};$
3) $\left(-\frac{1}{5}\right)^3=$
$= −\frac{1}{5}\cdot\left(-\frac{1}{5}\right)\cdot\left(-\frac{1}{5}\right)=−\frac{1}{125};$
4) $\left(1\frac{1}{2}\right)^3=\left(\frac{3}{2}\right)^3=\frac{3\cdot3\cdot3}{2\cdot2\cdot2}=$
$= \frac{27}{8}=3\frac{3}{8}.$