Toán Lớp 6: a) ( – 28 ) + (-35) – 92 + (-82)
b) 15-(-38)-(-55)-(+47)
Bài 2 tính hợp lý
A) (62-81) – (12-59+9)
B) 39+ ( 13 -26 ) – ( 62 + 39 )
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Toán Lớp 6: a) ( – 28 ) + (-35) – 92 + (-82)
b) 15-(-38)-(-55)-(+47)
Bài 2 tính hợp lý
A) (62-81) – (12-59+9)
B) 39+ ( 13 -26 ) – ( 62 + 39 )
Comments ( 2 )
Giải đáp:
Bạn tham khảo nhé.
Lời giải và giải thích chi tiết:
$a)-\!28+(-35)-92+(-82)\\=(-28-92)+(-35-82)\\=-120+(-117)\\=-237\\b)\,15-(-38)-(-55)-(+47)\\=15+38+55-47\\=(15+55)+(38-47)\\=70+(-9)\\=61\\2.\\a)\,(62-81)-(12-59+9)\\=62-81-12+59-9\\=(62-12)+(-81-9)+59\\=50+(-90)+59\\=-40+59\\=19\\b)\,39+(13-26)-(62+39)\\=39+13-26-62-39\\=(39-39)+(13-26-62)\\=0+(-75)\\=-75$
a)(-28) + (-35) – 92 + (-82)
= -28 – 35 – 92 – 82
= – (28 + 35 + 92 + 82)
= – [(28 + 82) + (35 + 92)]
= – (110 + 127) = – 237.
b) 15 – (-38) + (-55) – (+47)
= 15 + 38 – 55 – 47
= 53 – 55 – 47
= – (55 – 53) – 47
= – 2 – 47
= – (2 + 47) = – 49
Tính hợp lý
(62 – 81) – (12 – 59 + 9)
= 62 – 81 – 12 + 59 – 9
= (62 – 12) – (81 + 9) + 59
= 50 – 90 + 59
= – (90 – 50) + 59
= – 40 + 59
= 59 – 40
= 19
b) 39 + (13 – 26) – (62 + 39)
= 39 + 13 – 26 – 62 – 39
= (39 – 39) – (26 + 62) + 13
= 0 – 88 + 13
= – 88 + 13
= – (88 – 13)
= – 75.