Question

tính hợp lí nhất :

1, 35 . ( 14 - 23 ) - 23 . ( 14 - 35 ) 

2 , 27 . ( 13 - 16 ) - 16 .( 13 - 27 )

3, 44 . (-36 ) + 22 . ( - 28 )

Answer 1

1.

\(35\times\left(14-23\right)-23\times\left(14-35\right)\)

\(=35\times14-35\times23-23\times14+23\times35\)

\(=\left(23\times35-35\times23\right)+14\times\left(35-23\right)\)

\(=0+14\times12\)

\(=168\)

2.

\(27\times\left(13-16\right)-16\times\left(13-27\right)\)

\(=27\times13-27\times16-16\times13+16\times27\)

\(=13\times\left(27-16\right)+\left(27\times16-16\times27\right)\)

\(=13\times11+0\)

\(=143\)

3.

\(44\times\left(-36\right)+22\times\left(-28\right)\)

\(=22\times2\times\left(-36\right)+22\times\left(-28\right)\)

\(=22\times\left(-72\right)+22\times\left(-28\right)\)

\(=22\times\left[\left(-72\right)+\left(-28\right)\right]\)

\(=22\times\left(-100\right)\)

\(=-2200\)

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