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1) -(-17) - |-5|
=17-5
=12
2) - |+12| + (-14)
=-12+(-14)
=-26
3) -(+15) + |-7|
=-15+7
=-8
4) (-9) + -(-13)
=-9+13
=4
5) - (-12) + 0
=12+0
=12
6) - (-15) + (-15)
=15+(-15)
=0
7) -(-27) - (+27)
=27-27
=0
8) - (-13) - |-13|
=13-13
=0
9) - |-13| - |-17|
=-13-17
=-30
10) |-25| + |-17|
=25+17
=42
11) -18 + |-5|
=-18+5
=-13
12) |-20| - (-27)
=20+27
=47
13) - |-32| - (+15)
=-32-15
=-47
14) - (-25) - |-48|
=25-48
=-23
dễ mà
tick mk đi mk giải hết
nhưng ghi kết quả thui nha ^_^
![](https://rs.olm.vn/images/avt/0.png?1311)
1: =-2/9(15/17+2/17)=-2/9
2: \(=\dfrac{-6}{3}+\dfrac{-21}{90}\)
=-2-7/30=-67/30
3: \(=\dfrac{3}{4}\cdot\dfrac{7}{5}+\dfrac{9}{7}\cdot\dfrac{3}{2}\)
=21/20+27/14=417/140
4: =-25/13(5/19+14/19)=-25/13
5: =-7/5-45/21=-7/5-15/7=-124/35
1: =-2/9(15/17+2/17)=-2/9
2: =−63+−2190=−63+−2190
=-2-7/30=-67/30
3: =34⋅75+97⋅32=34⋅75+97⋅32
=21/20+27/14=417/140
4: =-25/13(5/19+14/19)=-25/13
5: =-7/5-45/21=-7/5-15/7=-124/35
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1:
a; \(\dfrac{5}{18}\) + \(\dfrac{8}{19}\) - \(\dfrac{7}{21}\) + (- \(\dfrac{10}{36}\) + \(\dfrac{11}{19}\) + \(\dfrac{1}{3}\)) - \(\dfrac{5}{8}\)
= \(\dfrac{5}{18}\) + \(\dfrac{8}{19}\) - \(\dfrac{1}{3}\) -\(\dfrac{10}{36}\) + \(\dfrac{11}{19}\) + \(\dfrac{1}{3}\) - \(\dfrac{5}{8}\)
= (\(\dfrac{5}{18}\) - \(\dfrac{10}{36}\)) + (\(\dfrac{8}{19}\) + \(\dfrac{11}{19}\)) - (\(\dfrac{1}{3}\) - \(\dfrac{1}{3}\)) - \(\dfrac{5}{8}\)
= (\(\dfrac{5}{18}\) - \(\dfrac{5}{18}\)) + \(\dfrac{19}{19}\) - 0 - \(\dfrac{5}{8}\)
= 0 + 1 - \(\dfrac{5}{8}\)
= \(\dfrac{3}{8}\)
b; \(\dfrac{1}{13}\) + (\(\dfrac{-5}{18}\) - \(\dfrac{1}{13}\) + \(\dfrac{12}{17}\)) - (\(\dfrac{12}{17}\) - \(\dfrac{5}{18}\) + \(\dfrac{7}{5}\))
= \(\dfrac{1}{13}\) - \(\dfrac{5}{18}\) - \(\dfrac{1}{13}\) + \(\dfrac{12}{17}\) - \(\dfrac{12}{17}\) + \(\dfrac{5}{18}\) - \(\dfrac{7}{5}\)
= (\(\dfrac{1}{13}\) - \(\dfrac{1}{13}\)) + (\(\dfrac{12}{17}\) - \(\dfrac{12}{17}\)) + (-\(\dfrac{5}{18}\) + \(\dfrac{5}{18}\)) - \(\dfrac{7}{5}\)
= 0 + 0 + 0 - \(\dfrac{7}{5}\)
= - \(\dfrac{7}{5}\)
Bài 1 c;
\(\dfrac{15}{14}\) - (\(\dfrac{17}{23}\) - \(\dfrac{80}{87}\) + \(\dfrac{5}{4}\)) + (\(\dfrac{17}{23}\) - \(\dfrac{15}{14}\) + \(\dfrac{1}{4}\))
= \(\dfrac{15}{14}\) - \(\dfrac{17}{23}\) + \(\dfrac{80}{87}\) - \(\dfrac{5}{4}\) + \(\dfrac{17}{23}\) - \(\dfrac{15}{14}\) + \(\dfrac{1}{4}\)
= (\(\dfrac{15}{14}-\dfrac{15}{14}\)) + (\(-\dfrac{17}{23}+\dfrac{17}{23}\)) - (\(\dfrac{5}{4}\) - \(\dfrac{1}{4}\)) + \(\dfrac{80}{87}\)
= 0 + 0 - 1 + \(\dfrac{80}{87}\)
= - \(\dfrac{7}{87}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a)\)Ta tách thành 2 vế của phép tính ra thành:
\(\left(5+7+9+11+13+15+17\right)+\left(3+8+13+18+23+28\right)\)
Ta gọi dãy \(\left(5+7+9+11+13+15+17\right)\)là \(S_1\)
\(\left(3+8+13+18+23+28\right)\) là dãy \(S_2\)
- Số số hạng của dãy \(S_1\)là:
\(\left(17-5\right)\div2+1=7\)( số hạng )
Tổng của dãy \(S_1\)là:
\(\left(17+5\right)\times7\div2=77\)
- Số số hạng của dãy \(S_2\)là:\(\left(3+8+13+18+23+28\right)\)
\(\left(28-3\right)\div5+1=6\)( số hạng )
Tổng của dãy \(S_2\)là:
\(\left(28+3\right)\times6\div2=93\)
Tổng của dãy \(S_1\)và \(S_2\)là:
\(77+93=170\)
Đáp số: \(170\)
\(b)\)Ta ghép thành 2 vế của phép tính ra thành:
\(\left(4+7+10+13+16+19\right)+\left(5+9+13+17+21+25\right)\)
Ta gọi dãy \(\left(4+7+10+13+16+19\right)\)là \(S_1\)
\(\left(5+9+13+17+21+25\right)\)là \(S_2\)
- Số số hạng của dãy số \(S_1\)là
\(\left(19-4\right)\div3+1=6\)( số hạng )
Tổng của dãy số \(S_1\)là:
\(\left(19+4\right)\times6\div2=69\)
- Số số hạng của dãy \(S_2\)là:\(\left(5+9+13+17+21+25\right)\)
\(\left(25-5\right)\div4+1=6\)( số hạng )
Tổng của dãy số \(S_2\)là:
\(\left(25+5\right)\times6\div2=90\)
Tổng của dãy \(S_1\) và \(S_2\)là:
\(69+90=159\)
Đáp số: \(159\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a, \(\begin{array}{l}A = \dfrac{{ - 3}}{{14}} + \dfrac{2}{{13}} + \dfrac{{ - 25}}{{14}} + \dfrac{{ - 15}}{{13}}\\A = \left( {\dfrac{{ - 3}}{{14}} + \dfrac{{ - 25}}{{14}}} \right) + \left( {\dfrac{2}{{13}} + \dfrac{{ - 15}}{{13}}} \right)\\A = \dfrac{{ - 3 + \left( { - 25} \right)}}{{14}} + \dfrac{{2 + \left( { - 15} \right)}}{{13}}\\A = \dfrac{{ - 28}}{{14}} + \dfrac{{ - 13}}{{13}}\\A = - 2 + (-1)\\A = - 3\end{array}\)
b,
Cách 1:
\(\begin{array}{l}B = \dfrac{5}{3}.\dfrac{7}{{25}} + \dfrac{5}{3}.\dfrac{{21}}{{25}} - \dfrac{5}{3}.\dfrac{7}{{25}}\\B = \left( {\dfrac{5}{3}.\dfrac{7}{{25}} - \dfrac{5}{3}.\dfrac{7}{{25}}} \right) + \dfrac{5}{3}.\dfrac{{21}}{{25}}\\B = 0 + \dfrac{5}{3}.\dfrac{{21}}{{25}}\\B = \dfrac{{5.21}}{{3.25}}\\B = \dfrac{7}{5}\end{array}\)
Cách 2:
\(B = \dfrac{5}{3}.\dfrac{7}{{25}} + \dfrac{5}{3}.\dfrac{{21}}{{25}} - \dfrac{5}{3}.\dfrac{7}{{25}}\\B = \dfrac{5}{3}.({\dfrac{7}{{25}} -\dfrac{7}{{25}} + \dfrac{{21}}{{25}}})\\B = \dfrac{5}{3}.\dfrac{{21}}{{25}}\\B = \dfrac{{5.21}}{{3.25}}\\B = \dfrac{7}{5}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
1: Ta có: \(2155-\left(174+2155\right)+\left(-68+174\right)\)
\(=2155-174-2155-68+174\)
=-68
2) Ta có: \(-25\cdot72+25\cdot21-49\cdot25\)
\(=-25\cdot\left(72-21+49\right)\)
\(=-25\cdot100=-2500\)
![](https://rs.olm.vn/images/avt/0.png?1311)
1) 2155 - (174 + 2155) + (-68 + 174)
= 2155 - 174 - 2155 - 68 + 174
= (2155 - 2155) + (-174 + 174) - 68
= 0 + 0 - 68
= -68
2) -25 . 72 + 25 . 21 - 49 . 25
= 25 . (-72) + 25 . 21 - 49 . 25
= 25 . (-72 + 21 - 25)
= 25 . (-76)
= -1900
3) 35 . (14 - 23) - 23 . (14 - 35)
= 35 . 14 - 35 . 23 - 23 . 14 + 23 . 35
= (35 . 14 - 23 . 14) + (-35 . 23 + 23 . 35)
= [14 . (35 - 23)] + 0
= 14 . 12
= 168
4) 8154 - (674 + 8154) + (-98 + 674)
= 8154 - 674 - 8154 - 98 + 674
= (8154 - 8154) + (-674 + 674) - 98
= 0 + 0 - 98
= -98
5) -25 . 21 + 25 . 72 + 49 . 25
= 25 . (-21) + 25 . 72 + 49 . 25
= 25 . (-21 + 72 + 49)
= 25 . 100
= 2500
6) 27 . (13 - 16) - 16 . (13 - 17)
= 27 . 13 - 27 . 16 - 16 . 13 + 16 . 17
= (27 . 13 - 16 . 13) + (-27 . 16 + 16 . 17)
= [13 . (27 - 16)] + [16 . (-27 + 17)]
= (13 . 11) + [16 . (-10)]
= 143 - 160
= -17
1) 2155-2155-(174-174)+-68=0+0+-68=-68
giờ mk ghi kq được ko
\(\left[\left(-\dfrac{25}{13}\right)+\dfrac{5}{3}\right]+\left[\left(-\dfrac{14}{3}\right)+\left(-\dfrac{17}{13}\right)\right]\)
\(=\left(\dfrac{5}{3}-\dfrac{25}{13}\right)-\left(\dfrac{14}{3}+\dfrac{17}{13}\right)\)
\(=\dfrac{5}{3}-\dfrac{25}{13}-\dfrac{14}{3}-\dfrac{17}{13}\)
\(=-3-\dfrac{42}{13}=-\dfrac{81}{13}\)
bằng âm 7 nhé bạn