Question

Tính một cách hợp lí:

a) 29,42 + 20,58 - 34,23 + (-25,77);

b) (-212,49) - (87,51 - 99,9).

Answer 1

a) 29,42 + 20,58 - 34,23 + (-25,77)

=(29,42+20,58)+(-34,23+-25,77)

=50+-60

=-10

b) (-212,49) - (87,51 - 99,9) 

=-212,49-87,51+99,9

=(-212,49-87,51)+99,9

=-300+99,9

=-200,1

Answer 2

`a) 29,42 + 20,58 - 34,23 + (-25,77)`
`=29+0,42+20+0,58-34-0,23-25-0,77`
`=29+20-34-25+0,42+0,58-(0,23+0,77)`
`=49-59+1-1`
`=-10`
`b) (-212,49) - (87,51 - 99,9).`
`=-212,49-87,51+99,9`
`=-(212,49+87,51)+99,99=`
`=-299,9+99,9`
`=-200`

Answer 3

a) 29,42+20,58-34,23+(-25,77)

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