Tính hợp lý ( là tính nhanh )
a) ( – 37 ) – 14 – 26 +37
b) ( -15 ) – 23 – ( – 85 ) – 77
c ) ( – 24 ) + 4 + ( – 6 ) + 26
d ) 33 – 14 – 26 – ( – 7 )
e ) ( – 719 – 45 ) – ( -55 – 719 )
f ) 111 + ( -11 + 27 )
Tính hợp lý ( là tính nhanh )
a) ( – 37 ) – 14 – 26 +37
b) ( -15 ) – 23 – ( – 85 ) – 77
c ) ( – 24 ) + 4 + ( – 6 ) + 26
d ) 33 – 14 – 26 – ( – 7 )
e ) ( – 719 – 45 ) – ( -55 – 719 )
f ) 111 + ( -11 + 27 )
a) ( – 37 ) – 14 – 26 +37
= [ ( – 37 ) + 37 ] – ( 14 + 26 )
= 0 – 40
= – 40
b ) ( -15 ) – 23 – ( – 85 ) – 77
= [ ( 85 ) + ( – 15 ) ] + [ ( -77) + ( -23 ) ]
= ( – 100 ) – 100
= – 200
c ) ( – 24 ) + 4 + ( – 6 ) + 26
= [ ( – 24 ) + ( – 6 )] + [ ( + 4 ) + 26 ]
= – 30 + ( + 30 )
= 0
d ) 33 – 14 – 26 – ( – 7 )
= [ 33 – 26 ] – [ 14 + ( – 7 ) ]
= 7 – 7
= 0
e ) ( – 719 – 45 ) – ( -55 – 719 )
= – 719 – 45 + 55 + 719 ( Phá ngoặc rồi kết hợp )
= [ ( – 719 ) + 719 ] + ( 55 – 45 ]
= 0 + 10
= 10
f ) 111 + ( -11 + 27 )
= [ 111 + ( -11 ) + 27
= 100 + 27
= 127
`( – 37 ) – 14 – 26 +37`
`=(37 – 37 ) – (14 + 26)`
`=0-40`
`=-40`
`(-15 ) – 23 – ( – 85 ) – 77`
`=(-15- -85 ) – (23 + 77)`
`=70-100`
`=-30`
`( – 24 ) + 4 + ( – 6 ) + 26`
`=(-24+4 ) – (6 -26)`
`=-20+20`
`=0`
`33 – 14 – 26 – ( – 7 )`
`=(33–7 ) – (14+26)`
`=-40+40`
`=0`
`( – 719 – 45 ) – ( -55 – 719 )`
`=( – 719 +719 ) +( 55 – 45 )`
`=0+10`
`=10`
`111 + ( -11 + 27 )`
`=27+(111 – 11 )`
`=27+100`
`=127`