Răspuns:
³⁾7/12+²⁾5/18=
12=2²·3
18=2·3²
cmmc(12,18)=2²·3²=36 numitorul comun al celor doua fractii
=21/36+10/36=31/36
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15/16-(-3/4)=15/16+⁴⁾3/4 =15/16+12/16=27/16
din regula semnelor stim ca - cu - da +
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-(-3/14)+2/21=³⁾3/14+²⁾2/21=9/42+4/42=13/42
14=2·7
21=3·7
cmmmc(14,21)=2·3·7=42 numitorul comun
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1 intreg 1/5·2 intregi 1/2
introducem intregii in fractie
1 intreg 1/5=(1·5+1)/5=6/5
2 intregi 1/2=5/2
²⁾6/5+⁵⁾5/2=12/10+25/10=37/10
