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`@` `\text {Ans}`
`\downarrow`
`a,`
\(\text{326 x 728 + 327 x 272}\)
`= 326 \times 728 + 326 \times 272 + 272`
`= 326 \times (728 + 272) + 272`
`= 326 \times 1000 + 272`
`= 362000 + 272`
`= 362272`
`b,`
\(\text{2008 x 867 + 2009 x 133}\)
`= 2008 \times 867 + 2008 \times 133 + 133`
`= 2008 \times (867 + 133) + 133`
`= 2008 \times 1000 + 133`
`= 2008000 + 133`
`= 2008133`
`c,`
\(\text{1235 x 6789 x (630 - 315 x 2 )}\)
`= 1235 \times 6789 \times (630 - 630)`
`= 1235 \times 6789 \times 0`
`= 0`
`d,`
\((m \div 1 - m \times 1 ) \div ( m \times 2008 + m + 2008)\)
`= (m - m) \div (m \times 2008 + m + 2008)`
`= 0 \div (m \times 2008 + m + 2008)`
`= 0`
a: =326*728+326*272+272
=326000+272
=326272
c: \(=1235\cdot6789\cdot\left(630-630\right)=0\)
d: \(=\left(m-m\right):\left(20009m+2008\right)=0\)
326 x 728+ 327 × 272 =
237328+88944= 326272
2008 ×867+ 2009× 133 =
1740936+267197=2008133
nhớ k minh nha
\(M:N=\frac{\frac{2008}{1}+\frac{2007}{2}+\frac{2006}{3}+...+\frac{2}{2007}+\frac{1}{2008}}{\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+...+\frac{1}{2008}+\frac{1}{2009}}\)
Ta có tử số bằng: 2008+2007/2+2006/3+2005/4+…..+2/2007+1/2008
(Phân tích 2008 thành 2008 con số 1 rồi đưa vào các nhóm)
= (1 + 2007/2) + (1 + 2006/3) + (1 + 2005/4) +... + (1 + 2/2007) + ( 1 + 1/2008) + (1)
= 2009/2 + 2009/3 + 2009//4 + ……. + 2009/2007 + 2009/2008 + 2009/2009
= 2009 x (1/2 + 1/3 + 1/4 + ... + 1/2007 + 1/2008 + 1/2009)
Mẫu số: 1/2 + 1/3 + 1/4 + ... + 1/2007 + 1/2008 + 1/2009
\(\Rightarrow M:N=\frac{2009.\left(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+...+\frac{1}{2008}+\frac{1}{2009}\right)}{\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+...+\frac{1}{2008}+\frac{1}{2009}}=2009\)
a.326.728+327.272
=326.728+326.272+272
=326.(728+272) +272
=326.1000 +272
=326000+272
=326272
B, 1235.6789.(630-315.2)
=1235.6789.(630- 630)
=1235.6789.0
=0
C, 2008.867+2009.133
=2008.867+2008.133 +133
=2008.(867+133)+133
=2008.1000 +133
=2008000+133
=2008133
D, (m:1-m*1) : (m*2008+m+2008)
= (m-m) : (m*2008+m+2008)
= 0 : (m*2008+m+2008)
=0