1/2 - 3/4 - (-1/3) + 1/69 - 2/9 + 1/6 - 1/36
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\(B=\left(\dfrac{-5}{3}+\dfrac{2}{5}\right):\dfrac{4}{5}+\left(\dfrac{-1}{3}+\dfrac{8}{5}\right):\dfrac{4}{5}\)
\(B=\dfrac{-5}{3}+\dfrac{2}{5}:\dfrac{4}{5}+\dfrac{-1}{3}+\dfrac{8}{5}:\dfrac{4}{5}\)
\(B=\left(\dfrac{-5}{3}+\dfrac{-1}{3}\right)+\left(\dfrac{2}{5}+\dfrac{8}{5}\right):\dfrac{4}{5}\)
\(B=\left[\left(-2\right)+2\right]:\dfrac{4}{5}\)
\(B=0:\dfrac{4}{5}=0\)
![](https://rs.olm.vn/images/avt/0.png?1311)
15: A= 1/3-3/4+3/5+1/2007-1/36+1/15-2/9
Sửa đề:
A=-3/4-2/9-1/36+1/3+3/5+1/15+1/2007
=-27/36-8/36-1/36+5/15+9/15+1/15+1/2007
=-1+1+1/2007=1/2007
16:
\(A=\dfrac{1}{3}+\dfrac{3}{5}+\dfrac{1}{15}-\dfrac{3}{4}-\dfrac{2}{9}-\dfrac{1}{36}+\dfrac{1}{64}\)
\(=\dfrac{5+9+1}{15}+\dfrac{-27-8-1}{36}+\dfrac{1}{64}\)
=1/64
17:
=1/2-1/2+2/3-2/3+3/4-3/4+4/5-4/5+5/6-5/6-6/7
=-6/7
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a, 100 + 98 + 96 + ... + 2 - 9 7 - 95 - .. -1
= 100 + (98 - 97) + (96-95) + ... + + ... + (2 - 1)
= 100 + 1 + 1 + 1 +.. +1
= 100 + 1 x49
= 100 + 49
= 149
b , 1 + 2 - 3 - 4 + 5 + 6 - .... -299 - 330 +301 + 302
=( 1 + 2 - 3) + ( -4 + 5 + 6 -7 ) +... +(298 - 299 -300 +301 ) + 302
= 0 + 0 + .. + 0 + 302
= 302
c) 2 . 31 . 12 + 4 . 6 . 42 + 8 . 27 . 3
=24.31+24.42+24.27
=24.(31+42+27)
=24.100
=2400
d)
=36x(28+82)+64x(69+41)
=36x110+64x110
=110x(26+64)
=110x100
=11000
d) dãy tính trên có số số tự nhiên là: (99-1):2+1=50(số)
99-97+95-93+91-89+...+7-5+3-1(50:2=25 cặp)
(99-97)+(95-93)+(91-89)+...+(7-5)+(3-1) (25 cặp)
2+2+2+2+2+...+2+2(25 số 2)
2x25=50
![](https://rs.olm.vn/images/avt/0.png?1311)
Ý bạn là mỗi phép tính phải thêm dấu và ....để kết quả bằng 6 phải không ạ
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1 :
a) 37581 - 9999 = 37581 - 10000 - 1 = 27581 - 1 = 27580
k cho mình nha bạn !
a)37581-9999=37581-(9999+1-1)=37581-(10000+1)=37581-10000-1=27581+1=27582
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{-7}{9}+\dfrac{-2}{9}=\dfrac{-9}{9}=-1\)
\(\dfrac{15}{4}-\dfrac{-3}{4}=\dfrac{18}{4}=\dfrac{9}{2}\)
\(\dfrac{1}{6}-\dfrac{1}{36}=\dfrac{6}{36}-\dfrac{1}{36}=\dfrac{5}{36}\)
\(1-\dfrac{3}{2}=\dfrac{2}{2}-\dfrac{3}{2}=\dfrac{-1}{2}\)
\(2-\dfrac{4}{5}=\dfrac{10}{5}-\dfrac{4}{5}=\dfrac{6}{5}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
1) \(\left|4-2x\right|.\dfrac{1}{3}=\dfrac{1}{3}\)
\(\left|4-2x\right|=\dfrac{1}{3}:\dfrac{1}{3}\)
\(\left|4-2x\right|=\dfrac{1}{3}.3\)
\(\left|4-2x\right|=1\)
=>\(4-2x=\pm1\)
+)\(TH1:4-2x=1\) +)\(TH2:4-2x=-1\)
\(2x=4-1\) \(2x=4-\left(-1\right)\)
\(2x=3\) \(2x=4+1\)
\(x=3:2\) \(2x=5\)
\(x=1,5\) \(x=5:2\)
Vậy x=1,5 \(x=2,5\)
Vậy x=2,5
2) \(\left(-3\right)^2:\left|x+\left(-1\right)\right|=-3\)
\(9:\left|x+\left(-1\right)\right|=-3\)
\(\left|x+\left(-1\right)\right|=9:\left(-3\right)\)
\(\left|x+\left(-1\right)\right|=-3\)
=> \(x+\left(-1\right)\) sẽ không có giá trị nào ( Vì giá trị tuyệt đối luôn luôn lớn hơn hoặc bằng 0 )
Vậy x = \(\varnothing\)
1/2 - 3/4 - ( - 1/3) + 1/69 - 2/9 + 1/6 - 1/36 = 1/69 nha bạn !
1/2 - 3/4 - (-1/3) + 1/69 - 2/9 + 1/6 - 1/36
= {1/2-3/4+1/6-1/36}+{1/3+1/69}-2/9
= {18-27+6-1/36}+{23+1/69}-2/9
= -4/36 + 24/69 -2/9
= -1/9 -2/9+24/69
= -1/3+24/69= -23+24/69=1/69
Bài này siêu siêu dễ ~~~~~~~~~~~~~~