Question

tính hợp lý :

a ) 12 - ( 4  + 105 - 13) + (4+105-3)

b) -15 + ( -17 + 21 - 35 ) +( 4 + 105 - 13 )

c ) ( / -5 / + /+7/ + /-9/) - ( /+5/ + /-7 / + 9 )

giải hộ mk cần gấp

 

Answer 1

\(a,12-\left(4+105-13\right)+\left(4+105-3\right)\)

\(=12-4-105+13+4+105-3\)

\(=12+\left(-4+4\right)+\left(-105+105\right)+\left(13-3\right)\)

\(=12+0+0+10\)

\(=22\)

\(b,-15+\left(-17+21-35\right)+\left(4+105-13\right)\)

\(=-15-17+21-35+4+105-13\)

\(=\left(-15-35\right)+\left(-17-13\right)+\left(21+4+105\right)\)

\(=-50-30+130\)

\(=-50+100\)

\(=50\)

\(c,\left(\left|-5\right|+\left|+7\right|+\left|-9\right|\right)-\left(\left|+5\right|+\left|-7\right|+9\right)\)

\(=\left(5+7+9\right)-\left(5+7+9\right)\)

\(=0\)