Question

5.1. Calcula: a) (2/5)–2 b) (–1/3)3 c) (–3/5)–4 d) –(–3/7)3

Answer 1

a)

$\left(\frac{2}{5}\right)-2\\=\frac{2}{5}-2\\=-\frac{2\cdot \:5}{5}+\frac{2}{5}\\=\frac{-2\cdot \:5+2}{5}\\-2\cdot \:5+2=-8\\=\frac{-8}{5}\\=-\frac{8}{5}$

b)

$\left(-\frac{1}{3}\right)\cdot \:3\\=-\frac{1}{3}\cdot \:3\\=-\frac{1\cdot \:3}{3}\\=-1$

c)

$\left(-\frac{3}{5}\right)-4\\=-\frac{3}{5}-4\\=-\frac{4\cdot \:5}{5}-\frac{3}{5}\\=\frac{-4\cdot \:5-3}{5}\\-4\cdot \:5-3=-23\\=\frac{-23}{5}\\=-\frac{23}{5}$

d)

$-\left(-\frac{3}{7}\right)\cdot \:3\\=\frac{3}{7}\cdot \:3\\=\frac{3\cdot \:3}{7}\\=\frac{9}{7}$