1. Calculati:
a) (-3) + 5 = - 3 + 5 = 2
b) 7 + (-9) = 7 - 9 = -2
e) 21 + (-17) = 21 - 17 = 4
f) (-19) + 12 = 12 - 19 = -7
i) (-7) - 12 = (-7) + (-12) = -19
j) (-6) - 18 = (-6) + (-18) = -24
m) 18 - (-20) = 18 + 20 = 38
n) 14 - (-21) = 14 + 21 = 35
2. Calculati:
[tex]a) \quad \dfrac{9}{4}+\dfrac{3}{2}= \dfrac{9+3 \cdot 2}{4}= \red{ \dfrac{15}{4}}[/tex]
[tex]b) \quad \dfrac{5}{6}-\dfrac{4}{3}=\dfrac{5-4\cdot 2}{6}=\dfrac{-3}{6}=\red {-\dfrac{1}{2}}[/tex]
[tex]e) \quad 2\dfrac{3}{8} +\Big(-\dfrac{13}{6}\Big)= \dfrac{2 \cdot 8 +3}{8}-\dfrac{13}{6}=\dfrac{19}{8}-\dfrac{13}{6} \\ = \quad \dfrac{19 \cdot 3-13 \cdot 4}{24}=\dfrac{57-52}{24}=\red{ \dfrac{5}{24}}[/tex]
[tex]f)\quad \Big( -\dfrac{7}{4}\Big)-1\dfrac{3}{14} = -\dfrac{7}{4}-\dfrac{1\cdot 14+3}{14}=-\dfrac{7}{4}-\dfrac{17}{14}\\= \quad -\dfrac{7 \cdot 7}{28}- \dfrac{17 \cdot 2}{28}=\dfrac{-49-34}{28}=\red {-\dfrac{83}{28}}[/tex]
