\(\frac{7,9-14}{3-17}\)
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3/14 × 5/17 + 11/14 × 5/17 + 12/17 × 5/16 + 12/17 × 11/16
= 5/17 × ( 3/14 + 11/14) + 12/17 × ( 5/16 + 11/16)
= 5/17 × 1 + 12/17 × 1
= 5/17 + 12/17
= 1
3/14 × 5/17 + 11/14 × 5/17 + 12/17 × 5/16 + 12/17 × 11/16
= 5/17 × ( 3/14 + 11/14) + 12/17 × ( 5/16 + 11/16)
= 5/17 × 1 + 12/17 × 1
= 5/17 + 12/17
= 1

A=\(\frac{3x5}{15x9}x\frac{17x14}{-18x17}=9x\frac{-7}{9}=-7\)

\(3\frac{14}{19}+\frac{13}{17}+\frac{35}{43}+6\)
\(=\frac{71}{19}+\frac{13}{17}+\frac{35}{43}+6\)
\(=\frac{1454}{323}+\frac{35}{43}+6\)
\(=5,...+6\)
\(=11,...\)
\(Bai2a\)\(A=\frac{\sqrt{3}-\sqrt{6}}{1-\sqrt{2}}-\frac{2+\sqrt{8}}{1+\sqrt{2}}\)
\(=\frac{\sqrt{3}\left(1-\sqrt{2}\right)}{1-\sqrt{2}}-\frac{2\left(1+\sqrt{2}\right)}{1+\sqrt{2}}\)
\(=\sqrt{3}-2\)
\(VayA=\sqrt{3}-2\)

Bài 1:
A = \(\frac15\) + \(\frac{3}{17}\) - \(\frac43\) + (\(\frac45\) - \(\frac{3}{17}\) + \(\frac13\)) - \(\frac17\) + (- \(\frac{14}{30}\))
A = \(\frac15\) + \(\frac{3}{17}\) - \(\frac43\) + \(\frac45\) - \(\frac{3}{17}\) + \(\frac13\) - \(\frac17\) - \(\frac{14}{30}\)
A = (\(\frac15\) + \(\frac45\)) + (\(\frac{3}{17}\) - \(\frac{3}{17}\)) - (\(\frac43-\frac13\)) - \(\frac{30}{210}\) - \(\frac{98}{210}\)
A = 1 + 0 - 1 - (\(\frac{30}{210}+\frac{98}{210}\))
A = 1 - 1 - \(\frac{228}{210}\)
A = 0 - \(\frac{128}{210}\)
A = - \(\frac{64}{105}\)
Bài 2:
B= (\(\frac58\) - \(\frac{4}{12}\) + \(\frac32\)) - (\(\frac58\) + \(\frac{9}{13}\)) - (\(\frac{-3}{2}\)) + \(\frac{7}{-15}\)
B = \(\frac58\) - \(\frac{4}{12}\) + \(\frac32\) - \(\frac58\) - \(\frac{9}{13}\) + \(\frac32\) - \(\frac{7}{15}\)
B = (\(\frac58\) - \(\frac58\)) + (\(\frac32\) + \(\frac32\)) - (\(\frac13\) + \(\frac{9}{13}\) + \(\frac{7}{15}\))
B = 0 + 3 - (\(\frac{65}{195}\) + \(\frac{135}{195}\) + \(\frac{91}{195}\))
B = 3 - (\(\frac{200}{195}\) + \(\frac{91}{195}\))
B = 3 - \(\frac{97}{65}\)
B = \(\frac{195}{65}\) - \(\frac{97}{65}\)
B = \(\frac{98}{65}\)

4/17 x 2 = 8/17.
Tính bằng cách thuận tiện:
8,3 x 7,9 + 7,9 x 1,7
= ( 8,3 + 1,7 ) x 7,9
= 10 x 7,9
= 79.
3,25 x 0,1
= 3,25 : 10
= 0,325.
4/17*2=8/17
8,3*7,9+7,9*1,7=7,9*(8,3+1,7)=7,9*10=79
3,25*0,1=0,325
\(\frac{7,9-14}{3-17}=\frac{-6,1}{-14}=\frac{61}{140}\)
\(\frac{7,9-14}{3-17}\)= \(\frac{-6,1}{-14}\)= \(\frac{4}{35}\)