Question

tính bằng cách hợp lý :

124 + ( -52 ) . 124 + (-124) . (-47)

-55 . 78 + 13 (-78) - 78 .(-65)

 

Answer 1

\(a,124+\left(-52\right).124+\left(-124\right).\left(-47\right)\\ =124+\left(-52\right).124+124.47\\ =124.\left[1+\left(-52\right)+47\right]\\ =124.4\\ =-496\)

\(b,-55.78+13.\left(-78\right)-78.\left(-65\right)\\ =-55.78+\left(-13\right).78-78.\left(-65\right)\\ =\left[-55+\left(-13\right)-\left(-65\right)\right].78\\ =-3.78\\ =-234\)

Answer 2

124 + ( -52 ) . 124 + (-124) . (-47)

=124+(-52)*124+124*47

=124*[1+(-52)+47]

=124*(-4)

=-496

 

-55 . 78 + 13 *(-78) - 78 .(-65)

=-55*78+(-13)*78-78*(-65)

=78*[-55+(-13)-(-65)]

=78*(-3)

=-234