Toán Lớp 6: Bài 6. Bỏ dấu ngoặc rồi tính
a) (15 + 37) + (52 – 37 – 17)
b) 938 – 42 + 14) – (25 – 27 – 15)
c) – ( 21 – 32) – ( – 12 + 32)
d) – (12 + 21 – 23) – (23 – 21 + 10)
e) (57 – 725) – (605 – 53)
f) (55 + 45 + 15) – (15 – 55 + 45)
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a){\rm{ }}\left( {15{\rm{ }} + {\rm{ }}37} \right){\rm{ }} + {\rm{ }}\left( {52{\rm{ }}-{\rm{ }}37{\rm{ }}-{\rm{ }}17} \right){\rm{ }}\\
= 15 + 37 + 52 – 37 – 17\\
= 15 + \left( {37 – 37} \right) + 52 – 17\\
= 15 + 0 + 52 – 17\\
= 50\\
b){\rm{ (}}938{\rm{ }}-{\rm{ }}42{\rm{ }} + {\rm{ }}14){\rm{ }}-{\rm{ }}\left( {25{\rm{ }}-{\rm{ }}27{\rm{ }}-{\rm{ }}15} \right){\rm{ }}\\
= 938{\rm{ }}-{\rm{ }}42{\rm{ }} + {\rm{ }}14 – 25 + 27 + 15\\
= 896 + 14 – 25 + 27 + 15\\
= 910 – 25 + 27 + 15\\
= 885 + 27 + 15\\
= 912 + 15\\
= 927\\
c){\rm{ }}-{\rm{ }}\left( {{\rm{ }}21{\rm{ }}-{\rm{ }}32} \right){\rm{ }}-{\rm{ }}\left( {{\rm{ }} – {\rm{ }}12{\rm{ }} + {\rm{ }}32} \right){\rm{ }}\\
= – 21 + 32 + 12 – 32\\
= 11 + 12 – 32\\
= 23 – 32\\
= – 9\\
d){\rm{ }}-{\rm{ }}\left( {12{\rm{ }} + {\rm{ }}21{\rm{ }}-{\rm{ }}23} \right){\rm{ }}-{\rm{ }}\left( {23{\rm{ }}-{\rm{ }}21{\rm{ }} + {\rm{ }}10} \right){\rm{ }}\\
= – 12 – 21 + 23 – 23 + 21 – 10\\
= – 33 + 23 – 23 + 21 – 10\\
= – 10 – 23 + 21 – 10\\
= – 33 + 21 – 10\\
= – 12 – 10\\
= – 22\\
e){\rm{ }}\left( {57{\rm{ }}-{\rm{ }}725} \right){\rm{ }}-{\rm{ }}\left( {605{\rm{ }}-{\rm{ }}53} \right){\rm{ }}\\
= 57 – 725 – 605 + 53\\
= \left( {57 + 53} \right) – \left( {725 + 605} \right)\\
= 110 – 1330\\
= – 1220\\
f){\rm{ }}\left( {55{\rm{ }} + {\rm{ }}45{\rm{ }} + {\rm{ }}15} \right){\rm{ }}-{\rm{ }}\left( {15{\rm{ }}-{\rm{ }}55{\rm{ }} + {\rm{ }}45} \right)\\
= 55 + 45 + 15 – 15 + 55 – 45\\
= 100 + 0 + 10\\
= 110
\end{array}\]