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1.
156.72+156.28
=156.(72+28)
=156.100
=15600
2.
32.(-39)+16.(-22)
=16.2.(-39)+16.(-22)
=16.[2.(-39)+(-22)]
=16.(-100)
=-1600
3.
-1945-(567-1945)
=-1945-567+1945
=-1945+1945-567
=0-567
=-567
4.
184.33+67.184
=184.(33.67)
=184.100
=18400
5.
44.(-36)+22.(-28)
=2.22.(-36)+22.(-28)
=22.[2.(-36)+(-28)]
=22.(-100)
=-2200
học tốt nhé
Câu 1:
a: =>-2x-x+17=34+x-25
=>-3x+17=x+9
=>-4x=-8
hay x=2
b: =>17x+16x+27=2x+43
=>33x+27=2x+43
=>31x=16
hay x=16/31
c: =>-2x-3x+51=34+2x-50
=>-5x+51=2x-16
=>-7x=-67
hay x=67/7
e: 3x-32>-5x+1
=>8x>33
hay x>33/8
Bài toán 1 : Tìm x nguyên biết.
a. 3 ≤ x – 2 < 5
=>3-2 < x-2 < 5-2
=>1 < x < 3
=>x=1
Vậy x=1
b. 0 ≤ x – 5 ≤ 2
=>0-5 < x-5 < 2-5
=>-5 < x < -3
=>x=-4
Vậy x=-4
Bài toán 2 : Tính hợp lý.
a. 4567 + (1234 – 4567) -4
=4567+1234-4567-4
=(4567-4567)+(1234-4)
=0+1230
=1230
b. 2001 – (53 + 1579) – (-53)
=2001-53-1579+53
=(2001-1579)+(-53+53)
=422+0
=422
c. 35 – 17 + 2017 – 35 + (-2017)
=(35-35)+[2017+(-2017)]-17-35
=0+0-17-35
=0-17-35
=-52
d. 37 + (-17) – 37 + 77
=(37-37)+[-17+77]
=0+60
=60
e. –(-219) + (-219) – 401 + 12
=0-401+12
=-389
f. |-85| – (-3).15
=85+3.15
=85+45
=130
g. 11.107 + 11.18 – 25.11
=11.(107+18-25)
=11.100
=1100
h. 115 – (-85) + 53 – (-500 + 53)
=115+85+53+500-53
=(53-53)+(115+85+500)
=0+700
=700
k. (-18) + (-31) + 98 + |-18| + (-69)
=-18-31+98+18-69
=(-18+18)+(-31-69)+98
=0+(-100)+98
=-100+98
=-2
Bài toán 4 : Tìm x, biêt.
a. 5x – 16 = 40 + x
5x - x = 40 + 16
4x = 56
x = 56 : 4
x=14
b. 4x – 10 = 15 – x
4x + x = 15 + 10
5x = 25
x = 25 : 5
x = 5
c. -12 + x = 5x – 20
-12 + 20 = 5x - x
8 = 4x
x = 8 : 4
x = 2
d. 7x – 4 = 20 + 3x
7x - 3x = 20 + 4
4x=24
x=24:4
x=6
e. 5x – 7 = – 21 – 2x
5x + 2x = -21+7
7x = -14
x = -14 : 7
x = -2
f. x + 15 = 7 – 6x
x + 6x = 7 - 15
7x = -8
x = -8/7
g. 17 – x = 7 – 6x
17 - 7 = -6x + x
10 = -7x
x=10/-7
h. 3x + (-21) = 12 – 8x
3x + 8x = 12 + 21
11x = 33
x = 33:11
x=3
k. 125 : (3x – 13) = 25
3x-13=125:25
3x-13=5
3x=5+13
3x=18
x=18:3
x=6
l. 541 + (218 – x) = 735
218-x=735-541
218-x=693
x=218-693
x=-475
a) \(\dfrac{2}{3}x-\dfrac{1}{2}=\dfrac{1}{10}\)
\(\dfrac{2}{3}x=\dfrac{1}{10}+\dfrac{1}{2}=\dfrac{3}{5}\)
\(x=\dfrac{3}{5}:\dfrac{2}{3}=\dfrac{9}{10}\)
b) \(\dfrac{39}{7}:x=13\)
\(x=\dfrac{\dfrac{39}{7}}{13}=\dfrac{3}{7}\)
c) \(\left(\dfrac{14}{5}x-50\right):\dfrac{2}{3}=51\)
\(\dfrac{14}{5}x-50=51\cdot\dfrac{2}{3}=34\)
\(\dfrac{14}{5}x=34+50=84\)
\(x=\dfrac{84}{\dfrac{14}{5}}=30\)
d) \(\left(x+\dfrac{1}{2}\right)\left(\dfrac{2}{3}-2x\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{1}{2}=0\\\dfrac{2}{3}-2x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{1}{2}\\x=\dfrac{1}{3}\end{matrix}\right.\)
e) \(\dfrac{2}{3}x-\dfrac{1}{2}x=\dfrac{5}{12}\)
\(\dfrac{1}{6}x=\dfrac{5}{12}\)
\(x=\dfrac{5}{12}:\dfrac{1}{6}=\dfrac{5}{2}\)
g) \(\left(x\cdot\dfrac{44}{7}+\dfrac{3}{7}\right)\dfrac{11}{5}-\dfrac{3}{7}=-2\)
\(\left(x\cdot\dfrac{44}{7}+\dfrac{3}{7}\right)\cdot\dfrac{11}{5}=-2+\dfrac{3}{7}=-\dfrac{11}{7}\)
\(x\cdot\dfrac{44}{7}+\dfrac{3}{7}=-\dfrac{11}{7}:\dfrac{11}{5}=-\dfrac{5}{7}\)
\(\dfrac{44}{7}x=-\dfrac{5}{7}-\dfrac{3}{7}=-\dfrac{8}{7}\)
\(x=-\dfrac{8}{7}:\dfrac{44}{7}=-\dfrac{2}{11}\)
h) \(\dfrac{13}{4}x+\left(-\dfrac{7}{6}\right)x-\dfrac{5}{3}=\dfrac{5}{12}\)
\(\dfrac{25}{12}x-\dfrac{5}{3}=\dfrac{5}{12}\)
\(\dfrac{25}{12}x=\dfrac{5}{12}+\dfrac{5}{3}=\dfrac{25}{12}\)
\(x=1\)
Mỏi tay woa bn làm nốt nha!!
1) x - 2 = -6
x = -6 + 2
x = -4
2) -5 . x - ( -3 ) =13
-5 . x = 13 + ( -3 )
-5 . x = 10
x = 10 : ( -5 )
x = -2
a)x-2=6-5x-16
6x= -8
x= -4/3
b)-5x-(-3)-x=13-x
-5x+3-x=13-x
-5x=10
x=-2
c)15-(x-7)=-21-x
15-x+7=-21-x
22=-21 ( vô lí)
x không có giá trị
D)3x+17=2+3x+15
17=17
x có vô số giá trị
e) x-45-(x-9)=-35-x
x-45-x+9=-35-x
-x=1
x=-1
f) -5+x=15-x-2x
4x=20
x=5
g) 2x-(-17) =15
2x+17=15
2x=-2
x=-1
trả lơi giúp mk vs ạ
a) \(156.72+28.156\)
\(=156\left(72+28\right)\)
\(=156.100\)
\(=15600\)
b) \(32.\left(-39\right)+16.\left(-22\right)\)
\(=16.2.\left(-39\right)+16.\left(-22\right)\)
\(=16.\left(-78\right)+16.\left(-22\right)\)
\(=16.\left(-78-22\right)\)
\(=16.\left(-100\right)\)
\(=-1600\)