Question

4. calculați
a)1/3 - 2/3
b) -1/3 + (-2/3)
c) -1/3 - (-2/3)
d) 1/5 +(-3/15)
e) -1/2 + (-3/8)
f)-1/5 - (-7/10
va rogg ​

Answer 1

a)

$\frac{1}{3} - \frac{2}{3} = \frac{1 - 2}{3} = \frac{ - 1}{3} = - \frac{1}{3}$

c)

$- \frac{1}{3} - ( - \frac{2}{3} ) = - \frac{1}{3} + \frac{2}{3} = \\ \\ \frac{ - 1 + 2}{3} = \frac{1}{3}$

b)

$- \frac{1}{3} + ( - \frac{2}{3} ) = - \frac{1}{3} - \frac{2}{3} = \frac{ - 1 - 2}{3} = - \frac{3}{3} = - 1$

d)

${}^{3)} \frac{1}{5} + ( - \frac{3}{15} ) = \frac{1 \times 3}{5 \times 3} - \frac{3}{15} = \\ = \frac{3}{15} - \frac{3}{15} = 0$

e)

${}^{4)} - \frac{1}{2} + ( - \frac{3}{8} ) = - \frac{1 \times 4}{2 \times 4} - \frac{3}{8} = \\ \\ = - \frac{4}{8} - \frac{3}{8} = \frac{ - 4 - 3}{8} = - \frac{7}{8}$

f)

${}^{2)} - \frac{1}{5} - ( - \frac{7}{10}) = - \frac{1 \times 2}{5 \times 2} + \frac{7}{10} = \\ \\ = - \frac{2}{10} + \frac{7}{10} = \frac{ - 2 + 7}{10} = \\ \\ = \frac{5}{10} {}^{(5} = \frac{5 \div 5}{10 \div 5} = \frac{1}{2}$