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a,
5,3 - (-5,1)+(-5,3) + 4,9;
\(\begin{array}{l}= 5,3 + 5,1 +(-5,3)+4,9 = \left[ {5,3 + \left( { - 5,3} \right)} \right] + \left( {5,1 + 4,9} \right)\\ = 0 + 10 = 10\end{array}\)
b,
(2,7 - 51,4) - (48,6 - 7,3)
\(\begin{array}{l} = 2,7 - 51,4 - 48,6 + 7,3\\ = \left( {2,7 + 7,3} \right) - \left( {51,4 + 48,6} \right)\\ = 10 - 100 = - 90\end{array}\)
c,
2,5. (-0,124) + 10, 124 . 2,5
= 2,5.(-0,124+10,124)
= 2,5.10
= 25
a: =5,3+5,1-5,3+4,9=10
b: =2,7-51,4-48,6+7,3
=10-100=-90
c: =2,5(-0,124+10,124)=2,5x10=25
d: =6,3-6,3+4.9=4,9
e: =15,3-21,5-4,5=-10,7
a) (-35,8) + (-17,2) + 16,4 + 4,6
= [ (-35,8) + (-17,2) ] + (16,4 + 4,6)
= -53 + 21
= -32
b) (5,3 - 2,8) - (4 + 5,3)
= 2,5 - 9,3
= -6,8
c) (34,72 + 32,28):5 - (57,25 - 36,05):2
= 67:5 - 21,2:2
= 13,4 - 10,6
= 2,8
d) 2,5.(-4,68) + 2,5.(-5,32)
= 2,5.[ (-4,68) + (-5,32) ]
= 2,5. (-10)
= -25
e) 5,36. 12,34 + (-5,36). 2,34
= 5,36. 12,34 - 5,36. 2,34
= 5,36. (12,34 - 2,34)
= 5,36. 10
= 53,6
a,-35,8+(-17,2)+16,4+4,6=(-35,8-17,2)+(16,4+4,6=-53+21=-32
b,(5,3-2,8)-(4+5,3)=5,3-2,8-4-5,3=(5,3-5,3)+(-2,8-4)=0-6,8=-6,8.
c,(34,72+32,28):5-(57,25-36,05):2=67:5-21,2:2=13.4-10.6=2,8
d,2,5(-4,68)+2,5(-5,32)=2,5(-4,68-5,32)=2,5x(-10)=-25
e,5,36x12,34+(-5,36)x2,34=5,36(12,34-2,34)=5,36x10=53,6
Vậy, 7x + 36 = 12 - x
=> 8x + 36 = 12
<=> x = (12 -36) ÷ 8 = -3
\(2\left(x+3\right)-4x=48\)
\(=>2x+6-4x=48\)
\(=>-2x=48-6\)
\(=>-2x=42\)
\(=>x=-21\)
Lệ Tự Nguyên Hào sai rồi nha
a/\(2\frac{1}{3}=\frac{2.3+1}{3}=\frac{7}{3}\)
\(4\frac{2}{5}=\frac{4.5+2}{5}=\frac{22}{5}\)
\(3\frac{1}{4}=\frac{3.4+1}{4}=\frac{13}{4}\)
\(9\frac{5}{7}=\frac{9.7+5}{7}=\frac{68}{7}\)
\(11\frac{3}{10}=\frac{11.10+3}{10}=\frac{113}{10}\)
b/\(5\frac{2}{17}=\frac{5.17+2}{17}=\frac{87}{17}\)
\(3\frac{6}{23}=\frac{3.23+6}{23}=\frac{75}{23}\)
\(7\frac{4}{9}=\frac{7.9+4}{9}=\frac{67}{9}\)
\(121\frac{15}{100}=\frac{121.100+15}{100}=\frac{12115}{100}\)
\(8\frac{3}{7}=\frac{8.7+3}{7}=\frac{59}{7}\)
Bài 22:
a) Ta có: \(A=\dfrac{1}{1\cdot2}+\dfrac{1}{2\cdot3}+\dfrac{1}{3\cdot4}+...+\dfrac{1}{2017\cdot2018}\)
\(=1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{2017}-\dfrac{1}{2018}\)
\(=1-\dfrac{1}{2018}=\dfrac{2017}{2018}\)
1, 15-(2x-3)=6
<=>2x-3=15-6
<=>2x=15-6+3
<=>2x=12
<=>x=12:2
<=>x=6
Vậy x=6
2, (x-2).3=3\(^2\)
<=>x-2=3\(^2\):3
<=>x-2=9:3
<=>x=9:3-2
<=>x=1
vậy x=1
3, (x+7)-25=13
<=>x+7=13+25
<=>x=13+25-7
<=>x=31
Vậy x=31
4, 450:(x-190)=50
<=>x-190=450:50
<=>x=450:50+/ 190
<=>x=199
Vậy x=199
5, 3 \(^x\)x 2=18
<=>3\(^x\)=18:2
<=>3\(^x\)=9=3\(^2\)
=>x=2
vậy x=2
10,2
bằng 10,2