\(56.\left(15+23\right)-15.\left(23+56\right)\)
\(=\left(56.15+56.23\right)-\left(15.23+15.56\right)\)
\(=56.15+56.23-15.23-15.56\)
\(=\left(56.15-56.15\right)+\left(56.23-15.23\right)\)
\(=0.\left[23.\left(56-15\right)\right]\)
\(=23.41\)
\(=943\)
a) 56.[ 15 + 23 ] - 15.[ 23 + 56 ]
= 56. 38 - 15. 79
= 2128 - 1185
= 943
b) 12.[ 47 - 23 ] + 23. [12 + 47]
= 12 . 24 + 23. 59
= 288 + 1357
= 1645
~ chúc bạn hok tốt nha ~ ^_^