\(A=11,44+12,56-30,05+1024\)

\(=24-30,56+1024\)

\(=-6,05+1024\)

\(=1017,95\)

59/20

1, 

\(\begin{array}{l}2,5.\left( {4,1 - 3 - 2,5 + 2.7,2} \right) + 4,2:2\\ = 2,5.\left( {4,1 - 3 - 2,5 + 14,4} \right) + 4,2:2\\ = 2,5.\left( {1,1 - 2,5 + 14,4} \right) + 2,1\\ = 2,5.\left( { - 1,4 + 14,4} \right) + 2,1\\ = 2,5.13 + 2,1\\ = 32,5 + 2,1\\ = 34,6\end{array}\)

2, 

Cách 1:

\(\begin{array}{l}2,86.4 + 3,14.4 - 6,01.5 + {3^2}\\ = 11,44 + 12,56 - 30,05 + 9\\ = \left( {11,44 + 12,56} \right) + \left( { - 30,05 + 9} \right)\\ = 24 + \left( { - 21,05} \right)\\ = 24 - 21,05\\ = 2,95\end{array}\)

Cách 2: 

\(\begin{array}{l}2,86.4 + 3,14.4 - 6,01.5 + {3^2}\\ = 4.(2,86+3,14) - 30,05 + 9\\ = 4.6 + \left( { - 30,05 + 9} \right)\\ = 24 + \left( { - 21,05} \right)\\ = 24 - 21,05\\ = 2,95\end{array}\)

-320

=28+32-28-32+5

=(28-28)+(32-32)+5

=5

28 - ( -32 ) + ( -28 ) - 32 + 5

= 28 + 32 + ( -28 ) - 32 + 5

= ( -28 + 28 ) + ( -32 + 32 ) + 5

= 0 + 0 + 5

= 5 

28-(-32)+(-28)-32+5

=[28+(-28)] +[(-32)+32]+5

= 0+0+5=5

mk tính nhanh

36:32 + 23.22 = 36-2 + 23+2 = 34 + 25 = 81 + 32 = 113

− 3 2 + 2 3 − − 5 2 + 4 3 =   9   +   8   –   25   +   64   =   56                                                                                                

5.42 - 18:32 = 5.16 – 18:9 = 80 - 2 = 78

Đáp án: C

4. 5 2 −6. 3 2  = 4.25−6.9 = 100−54 = 46