hộ mik với
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BÀI TẬP VỀ NHÀ
Bài 1. Thực hiện phép tính:
1) -\frac{3}{10} + \frac{7}{15} \times \frac{8}{8}
2) -\frac{7}{12} \cdot \frac{8}{15} \cdot \frac{2}{5}
3) -\frac{9}{51} \times \frac{17}{6} \times \frac{7}{6}
4) -\frac{4}{5} \cdot \left( -\frac{3}{4} \right) 1,5.
Bài 2. Thực hiện phép tính:
1) \left( 8 + \frac{1}{3} - \frac{3}{5} \right) - \left( 5 + 0,4 \right) - \left( \frac{2}{3} - 1 \right)
2) \left[ \left[ \frac{1}{2} - \frac{1}{3} \right] 3 - 1 \right] + \left( \frac{2}{3} \right)^2 \cdot \left( \frac{1}{3} \right)^2
Bài 3. Bỏ dấu ngoặc rồi tính hợp lí các tổng sau:
1) \frac{17}{11} - \left( \frac{6}{5} - \frac{16}{11} \right) + \frac{26}{5}
2) \left( -0,1 + \frac{16}{9} \right) - \left( \frac{20}{9} - 11,1 \right)
3) \frac{39}{5} + \left( \frac{9}{4} - \frac{9}{5} \right) - \left( \frac{5}{4} + \frac{6}{7} \right)
4) \left( 0,25 - 11,2 \right) - \left( 5,75 + 8,8 \right)
Bài 4. Tính hợp lí:
1) \frac{1}{7} + \frac{1}{7} + \frac{2}{7} + \frac{4}{
Bài `1`
`1)` `(-3)/10 + 7/15 . 3/8 `
`= (-3)/10 + ( (7.3)/(15.8))`
`= (-3)/10 + 7/40`
` = (-12)/40 + 7/40 = -1/8 `
`2)`` (-7)/12 - 8/15 : 2/5 `
`= (-7)/12 - 8/15 . 5/2`
` = (-7)/12 + ( (-8.5)/(15.2) )`
` = (-7)/12 - 4/3 `
`= (-7)/12 - 16/12 = -23/12 `
`3) (-9)/51 . 17/6 - 7/6 `
`= (((-9).17)/(51.6)) - 7/6`
`= -1/2 - 7/6 = -3/6 - 7/6 = -5/3`
`4) -1 4/5 : ((-3)/4).1,5 `
`= -9/5 . (-4)/3 . 3/2 `
`= 18/5 `
Bài `3`
`1) 17/11 - (6/5 - 16/11) + 26/5 `
`= 17/11 - 6/5 + 16/11 + 26/5`
`= (17/11 + 16/11) + (-6/5 + 26/5)`
`= 3 +4 = 7`
`2) (-0,1 + 16/9) - (20/9 -11,1)`
`= -0,1 + 16/9 - 20/9 +11,1`
`= (-0,1 +11,1) + (16/9 -20/9)`
`= 11 + (-4)/9 = 95/9`
`3) 39/5 + (9/4-9/5) - (5/4+6/7)`
`= 39/5 + 9/4-9/5 - 5/4-6/7`
`= (39/5 - 9/5) + (9/4 - 5/4) - 6/7 `
`= 6 + 1 - 6/7 = 43/7`
`4) (0,25 -11,2 ) -( 5,75 + 8,8)`
`= -10,95 - 14,55 = -25,5 `
Bài `4`
`1) 1/7. 1/5 + 1/7. 2/5 + 1/7. 4/5 `
`= 1/7 ( 1/5 +2/5 +4/5 ) = 1/7 . 7/5 = 1/5 `
`2) 4/9 . (-1)/19 +5/9 .(-1)/19 `
`= (-1)/19 . ( 4/9 + 5/9 ) = (-1)/19 . 1 = -1/19 `
Bài 1:
1: \(-\frac{3}{10}+\frac{7}{15}\cdot\frac38=-\frac{3}{10}+\frac75\cdot\frac18\)
\(=-\frac{3}{10}+\frac{7}{40}=-\frac{12}{40}+\frac{7}{40}=-\frac{5}{40}=-\frac18\)
2: \(-\frac{7}{12}-\frac{8}{15}:\frac25\)
\(=-\frac{7}{12}-\frac{8}{15}\cdot\frac52\)
\(=-\frac{7}{12}-\frac{40}{30}=-\frac{7}{12}-\frac43=-\frac{7}{12}-\frac{16}{12}=-\frac{23}{12}\)
3: \(-\frac{9}{51}\cdot\frac{17}{6}-\frac76\)
\(=-\frac96\cdot\frac{17}{51}-\frac76\)
\(=-\frac32\cdot\frac13-\frac76=-\frac12-\frac76=-\frac36-\frac76=-\frac{10}{6}=-\frac53\)
4: \(-1\frac45:\left(-\frac34\right)\cdot1,5\)
\(=-\frac95\cdot\frac{-4}{3}\cdot\frac32\)
\(=\frac95\cdot\frac43\cdot\frac32=\frac95\cdot\frac42=\frac95\cdot2=\frac{18}{5}\)
Bài 2:
1: \(\left(8+2\frac13-\frac35\right)-\left(5+0,4\right)-\left(2\frac13-1\right)\)
\(=8+\frac73-\frac35-5-0,4-\frac73+1\)
\(=\left(8-5+1\right)+\left(-\frac35-0,4\right)\)
=4-1
=3
2: \(\left\lbrace\left\lbrack\left(\frac12-\frac13\right)\cdot3-1\right\rbrack+\left(-\frac23\right)^2\right\rbrace:\left(\frac13\right)^2\)
\(=\left\lbrace\left\lbrack\frac16\cdot3-1\right\rbrack+\frac49\right\rbrace:\frac19\)
\(=\left(\frac12-1+\frac49\right)\cdot9=\left(-\frac12+\frac49\right)\cdot9=-\frac92+4=-\frac12\)
Bài 3:
1: \(\frac{17}{11}-\left(\frac65-\frac{16}{11}\right)+\frac{26}{5}\)
\(=\frac{17}{11}-\frac65+\frac{16}{11}+\frac{26}{5}\)
\(=\frac{33}{11}+\frac{20}{5}\)
=3+4=7
2: \(\left(-0,1+\frac{16}{9}\right)-\left(\frac{20}{9}-11,1\right)\)
\(=-\frac{1}{10}+\frac{16}{9}-\frac{20}{9}+11,1\)
\(=10-\frac49=\frac{90}{9}-\frac49=\frac{86}{9}\)
3: \(\frac{39}{5}+\left(\frac94-\frac95\right)-\left(\frac54+\frac67\right)\)
\(=\frac{39}{5}+\frac94-\frac95-\frac54-\frac67\)
\(=\frac{30}{5}+\frac44-\frac67=6+1-\frac67=6+\frac17=\frac{43}{7}\)
4: \(\left(0,25-11,2\right)-\left(5,75+8,8\right)\)
=0,25-11,2-5,75-8,8
=-5,5-20
=-25,5
Bài 4:
1: \(\frac17\cdot\frac15+\frac17\cdot\frac25+\frac17\cdot\frac45\)
\(=\frac17\left(\frac15+\frac25+\frac45\right)=\frac17\cdot\frac75=\frac15\)
2: \(\frac49\cdot\frac{-1}{19}+\frac59\cdot\frac{-1}{19}\)
\(=-\frac{1}{19}\cdot\left(\frac49+\frac59\right)\)
\(=-\frac{1}{19}\cdot\frac99=-\frac{1}{19}\)
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