Question

bài 2 : tính hợp lí

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

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

Answer 1

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

\(=50-60=-10\)

b) \(-\left(212,49+87,51\right)+99,9\)

\(=-300+99,9=-200,1\)

Answer 2

A)29.42+20.58−34.23+(−25.77)29.42+20.58−34.23+(−25.77) 

=29.42+20.58−34.23−25.77

=29.42+20.58−34.23−25.77

=(29.42+20.58)−(34.23+25.77)

=(29.42+20.58)−(34.23+25.77)

=50−60=50−60

=−10=−10

B).(−212.49)−(87.51−99.9)(−212.49)−(87.51−99.9) 

=−212.49−87.51+99.9

=−212.49−87.51+99.9

=−(212.49+87.51)+99.9

=−(212.49+87.51)+99.9

=−300+99.9=−300+99.9

=−(300−99.9)=−(300−99.9)

=−200.1