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Aplic 1. Efectuează înmulțirile (introducând mai întâi întregii în fracție, acolo unde es şi scrie rezultatele ca fracții ireductibile: a) 10. 7 20' e) 2-3; f) 3 / 10-24; 1.2. g) 1/12 - 1/3; 9 5' b) 27. 1: 5 18' c) 1·14; 21 d) 20-24; h) 12. 8 3' 8 12. 36 10' i): 3 42. 35 15' 1) - 5 k) 1/8 20 6 11. 1) 22 36 1.15. m) 23. 15: 19' n) 33/-146; 32 30' 0) 23-15 28 p) 4 1/2-23/3/20​

Răspuns :

Explicație pas cu pas:

Pentru a rezolva exercițiul, vom calcula fiecare înmulțire și apoi vom simplifica rezultatele la fracții ireductibile:

a) \(10 \frac{7}{20} \times 1 \frac{2}{3}\)

\(10 \frac{7}{20} = \frac{207}{20}\)

\(1 \frac{2}{3} = \frac{5}{3}\)

\(\frac{207}{20} \times \frac{5}{3} = \frac{207 \times 5}{20 \times 3} = \frac{1035}{60} = \frac{69}{4}\)

b) \(27 \frac{1}{5} \times 18\)

\(27 \frac{1}{5} = \frac{136}{5}\)

\(\frac{136}{5} \times 18 = \frac{136 \times 18}{5} = \frac{2448}{5}\)

c) \(1 \times 14 \times 21\)

\(1 \times 14 \times 21 = 294\)

d) \(20 \frac{24}{1} \times 8\)

\(20 \frac{24}{1} = 20 \times 24 = 480\)

e) \(2 \frac{3}{10} \times \frac{24}{1}\)

\(2 \frac{3}{10} = \frac{23}{10}\)

\(\frac{23}{10} \times 24 = \frac{23 \times 24}{10} = \frac{552}{10} = \frac{276}{5}\)

f) \(\frac{3}{10} \times 24 \times 12\)

\(\frac{3}{10} \times 24 = \frac{72}{10} = \frac{36}{5}\)

\(\frac{36}{5} \times 12 = \frac{36 \times 12}{5} = \frac{432}{5}\)

g) \(\frac{1}{12} - \frac{1}{3}\)

\(\frac{1}{12} - \frac{1}{3} = \frac{1}{12} - \frac{4}{12} = -\frac{3}{12} = -\frac{1}{4}\)

h) \(12 \frac{8}{3} \times 12 \frac{36}{10}\)

\(12 \frac{8}{3} = \frac{44}{3}\)

\(12 \frac{36}{10} = \frac{126}{10}\)

\(\frac{44}{3} \times \frac{126}{10} = \frac{44 \times 126}{3 \times 10} = \frac{5544}{30} = \frac{1848}{10} = 184 \frac{8}{10} = 184 \frac{4}{5}\)

i) \(3 \frac{42}{35} \times 15\)

\(3 \frac{42}{35} = 3 \frac{6}{35} = 3 \frac{6 \times 3}{35 \times 3} = 3 \frac{18}{105} = 3 \frac{6}{35} = 3 \frac{2}{35}\)

\(3 \frac{2}{35} \times 15 = \frac{3 \times 35 + 2}{35} \times 15 = \frac{107}{35} \times 15 = \frac{107 \times 15}{35} = \frac{1605}{35} = \frac{321}{7}\)

j) \(-5 \times 1 \frac{22}{36}\)

\(1 \frac{22}{36} = \frac{36 + 22}{36} = \frac{58}{36} = 1 \frac{22}{36} = 1 \frac{11}{18}\)

\(-5 \times 1 \frac{11}{18} = -5 \times \frac{18 + 11}{18} = -5 \times \frac{29}{18} = -\frac{145}{18}\)

k) \(\frac{1}{8} \times 20 \frac{6}{11}\)

\(20 \frac{6}{11} = \frac{226}{11}\)

\(\frac{1}{8} \times \frac{226}{11} = \frac{226}{88}\)

l) \(1 \frac{15}{23} \times 19\)

\(1 \frac{15}{23} = \frac{23 + 15}{23} = \frac{38}{23}\)

\(\frac{38}{23} \times 19 = \frac{38 \times 19}{23} = \frac{722}{23}\)

m) \(23 \frac{15}{19} \times 1\)

\(23 \frac{15}{19} = \frac{454}{19}\)

\(\frac{454}{19} \times 1 = \frac{454}{19}\)

n) \(\frac{33}{-146} \times \frac{32}{30}\)

\(\frac{33}{-146} \times \frac{32}{30} = \frac{33 \times 32}{-146 \times 30} = \frac{1056}{-4380} = -\frac{264}{1095}\)

o) \(23 \frac{15}{28}\)

\(23 \frac{15}{28} = \frac{651}{28}\)

p) \(4 \frac{1}{2} - \frac{23}{3 \times 20}\)

\(4 \frac{1}{2} = \frac{9}{2}\)

\(\frac{23}{3 \times 20} = \frac{23}{60} = \frac{23 \times 2}{60 \times 2} = \frac{46}{120} = \frac{23}{60}\)

\(\frac{9}{2} - \frac{23}{60} = \frac{270}{60} - \frac{23}{60} = \frac{247}{60}\)