a: =(21-22)+(23-24)=-1-1=-2
b: =125-115+99=10+99=109
c: \(=232-250-132=100-250=-150\)
d: \(=12-57+57+\left(-12\right)=0\)
a, 21 - 22 + 23 - 24
= ( 21 - 22 ) + ( 23 - 24 )
= -1 + (-1)
= -2
b, 125 - ( 115 - 99 )
= 125 - 115 + 99
= 10 + 99
= 109
c, 232 - ( 581 + 132 - 331 )
= 232 - 581 - 132 + 331
= ( 232 - 132 ) + ( 331 - 581 )
= 100 + ( - 250 )
= -150
d, [ 12 + (-57) ] - [ -57 - (-12) ]
= 12 - 57 + 57 + 12
= ( 12 + 12 ) + [ 57 + ( - 57 ) ]
= 24 + 0
= 24
\(a, 21 - 22 + 23 - 24\)
\(= ( 21 - 22 ) + ( 23 - 24 ) \)
\(= -1 + (-1) = -2\)
\(--------------\)
\(b, 125 - ( 115 - 99 )\)
\(= 125 - 115 + 99 \)
\(= (125 - 115) + 99 \)
\(= 10 + 99 = 109\)
\(--------------\)
\(c, 232 - ( 581 + 132 - 331 )\)
\(= 232 - 581 - 132 + 331 \)
\(= ( 232 - 132 ) - ( 581 - 331 )\)
\(= 100 - 250 = -150\)
\(--------------\)
\(d, [ 12 + (-57) ] - [ -57 - (-12) ]\)
\(= ( 12 − 57 ) − ( − 57 + 12 ) \)
\(= 12 − 57 + 57 − 12\)
\(= ( 12 − 12 ) + ( 57 − 57 )\)
\(= 0 + 0 = 0\)
\(\text{# Hàn Thiên Vy}\)