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Calculati in doua moduri:
a) (+5)·[(-4)-(-5)]
b)(-12+15-8)·(-9)


Răspuns :

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Vezi imaginea MILADYDANCECLUB
A1)(+5)×[(-4)-(-5)]=(+5)×(+1)=5; A2)(+5)×[(-4)-(-5)]=[(+5)×(-4)]-[(+5)×(-5)=(-20)-(-25)=5; B1)(-12+15-8)×(-9)=(-5)×(-9)=45; B2)(-12+15-8)×(-9)=[(-12)×(-9)]+[15×(-9)]-[(-8)×(-9)]=108-135+72=-27+72=45.