Question

thực hiện phép tính (có thể tính  thuận tiện)

a)(-123)-257+23+357+(-45)

b)(38-29+43)-(48+38)

Answer 1

\(a,=\left[\left(-123\right)+23\right]+\left(-257+357\right)-45=-100+100-45=-45\\ b,=38-29+43-48-38=-29+43-48=14-48=-34\)

Answer 2

`(-123)-257+23+357+(-45)`

`=-123 - 257 + 23 + 357 - 45`

`=(-123 - 257) + (23 + 357) - 45`

`=-380 + 380 - 45`

`=0-45`

`=-45`

________________________
`(38-29+43)-(48+38)`

`=38 - 29 + 43 - 48 - 38`

`=(38-38) - 29 + 43 - 48`

`=0 - 29 + 43 - 48`

`=-34`

Answer 3

\(a.\left(-123\right)-257+23+357+\left(-45\right)\)

\(=-380+380+\left(-45\right)=-45.\)

\(b.\left(38-29+43\right)-\left(48+38\right)\)

\(=52-86=-34.\)