Toán Lớp 6: Mọi người giúp mik với ạ
Bài 1:Tính hợp lí
a, 17 . ( 15 – 16 ) + 16 . ( 17 – 20 )
b, ( -29 ) . ( 85 – 47 ) – 85 . ( 47 – 29 )
c, ( -167 ) . (67 – 34) – 67 . (34 – 167)
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Toán Lớp 6: Mọi người giúp mik với ạ
Bài 1:Tính hợp lí
a, 17 . ( 15 – 16 ) + 16 . ( 17 – 20 )
b, ( -29 ) . ( 85 – 47 ) – 85 . ( 47 – 29 )
c, ( -167 ) . (67 – 34) – 67 . (34 – 167)
Comments ( 1 )
a)17.\left( {15 – 16} \right) + 16.\left( {17 – 20} \right)\\
= 17.15 – 17.16 + 16.17 – 16.20\\
= 17.15 – 16.20\\
= 5.\left( {17.3 – 16.4} \right)\\
= 5.\left( { – 13} \right)\\
= – 65\\
b)\\
\left( { – 29} \right).\left( {85 – 47} \right) – 85.\left( {47 – 29} \right)\\
= – 29.85 + 29.47 – 85.47 + 85.29\\
= \left( { – 29.85 + 85.29} \right) + 47.\left( {29 – 85} \right)\\
= 47.\left( { – 56} \right)\\
= – 2632\\
c)\\
\left( { – 167} \right).\left( {67 – 34} \right) – 67.\left( {34 – 167} \right)\\
= – 167.67 + 167.34 – 67.34 + 67.167\\
= \left( { – 167.67 + 67.167} \right) + 34.\left( {167 – 67} \right)\\
= 34.100\\
= 3400
\end{array}$