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a: \(61\cdot45+61\cdot23-68\cdot51\)
\(=61\left(45+23\right)-68\cdot51\)
\(=68\cdot61-68\cdot51\)
\(=68\left(61-51\right)=68\cdot10=680\)
b: \(3\cdot5^2-\left(75-4\cdot2^3\right)\)
\(=75-75+4\cdot8\)
\(=4\cdot8=32\)
c: \(36:\left\{2^2\cdot5-\left[30-\left(5-1\right)^2\right]\right\}\)
\(=\dfrac{36}{20-30+4^2}\)
\(=\dfrac{36}{-10+16}=\dfrac{36}{6}=6\)
d: \(\left(12\cdot49-3\cdot2^2\cdot7^2\right):\left(2020\cdot2021\right)\)
\(=\dfrac{\left(12\cdot49-12\cdot49\right)}{2020\cdot2021}=0\)
a) ( x + 74 ) - 318 = 2015
=> x + 74 = 2015 + 318
=> x + 74 = 2333
=> x = 2333 - 74
=> x = 2259
b) 3636 : ( 12 . x - 91 ) = 36
=> 12 . x - 91 = 3636 : 36
=> 12 . x - 91 = 101
=> 12 . x = 101 + 91
=> 12 . x = 192
=> x = 192 : 12
=> x = 16
c) ( x : 23 + 45 ) . 67 = 8911
=> x : 23 + 45 = 8911 : 67
=> x : 23 + 45 = 133
=> x : 23 = 133 - 45
=> x : 23 = 88
=> x = 88 . 23
=> x = 2024
Tìm x, biết :
a) ( x + 74) - 318 = 2015
(x + 74) = 2015 + 318
(x + 74) = 2333
x = 2333 - 742
x = 2259
b) 3636 : (12 . x - 91) = 36
12 . x - 91 = 3636 : 36
12. x - 91 = 101
12 . x = 101 + 91
12 . x = 192
x = 192 : 12
x = 16
c) ( x : 23 + 45) . 67 = 8911
(x : 23 + 45) = 8911 : 67
(x : 23 + 45) = 133
x : 23 = 133 - 45
x : 23 = 88
x = 88 . 23
x = 2024
. là nhân nha
a) 45 + x = 79 + 2x
=> 45 - 79 = 2x - x
=> - 34 = x
vậy x = -34
b) 15 - (x + 7) = (x - 8) +22
=> 15 - x - 7 = x - 8 + 22
=> 15 - 7 + 8 - 22 = x + x
=> 2x = -6
=> x = -3
vậy x = -3
c) |x| = 5
=> x = 5 hoặc x = -5
d) x - ƯCLN(16; 24) = 7
câu này đề kì kì
a) \(45+x=79+2x\)
\(\Rightarrow x-2x=79-45\)
\(\Rightarrow-x=34\)
\(\Rightarrow x=-34\)
Vậy \(x=-34\)
b) \(15-\left(x+7\right)=\left(x-8\right)+22\)
\(\Rightarrow15-x-7=x-8+22\)
\(\Rightarrow-x-x=-15+7-8+22\)
\(\Rightarrow-2x=6\)
\(\Rightarrow x=-3\)
Vậy \(x=-3\)
c) \(\left|x\right|=5\)
\(\Rightarrow\orbr{\begin{cases}x=5\\x=-5\end{cases}}\)
Vậy \(x\in\left\{5;-5\right\}\)
d) \(x-ƯCLN\left(16;24\right)=7\)
\(\Rightarrow x-8=7\)
\(\Rightarrow x=15\)
Vậy \(x=15\)
Bài 1:
1) Ta có: \(\left(-12\right)+6\cdot\left(-3\right)\)
\(=-12-18\)
=-30
2) Ta có: \(\left(36-2020\right)+\left(2019-136\right)-27\)
\(=36-2020+2019-136-27\)
\(=1-100-27\)
\(=-126\)
3) Ta có: \(\left(144-97\right)-\left(244-197\right)\)
\(=144-97-244+197\)
\(=-100+100=0\)
4) Ta có: \(\left(-24\right)\cdot13-24\cdot\left(-3\right)\)
\(=-24\cdot13+24\cdot3\)
\(=24\cdot\left(-13+3\right)\)
\(=24\cdot\left(-10\right)=-240\)
5) Ta có: \(54+55+56+57+58-\left(64+65+66+67+68\right)\)
\(=54+55+56+57+58-64-65-66-67-68\)
\(=\left(54-64\right)+\left(55-65\right)+\left(56-66\right)+\left(57-67\right)+\left(58-68\right)\)
\(=\left(-10\right)+\left(-10\right)+\left(-10\right)+\left(-10\right)+\left(-10\right)\)
=-50
6) Ta có: \(24\cdot\left(16-5\right)-16\cdot\left(24-5\right)\)
\(=24\cdot16-24\cdot5-16\cdot24+16\cdot5\)
\(=-24\cdot5+16\cdot5\)
\(=5\cdot\left(-24+16\right)\)
\(=-5\cdot8=-40\)
7) Ta có: \(47\cdot\left(23+50\right)-23\cdot\left(47+50\right)\)
\(=47\cdot23+47\cdot50-23\cdot47-23\cdot50\)
\(=47\cdot50-23\cdot50\)
\(=50\cdot\left(47-23\right)\)
\(=50\cdot24=1200\)
8) Ta có: \(\left(-31\right)\cdot47+\left(-31\right)\cdot52+\left(-31\right)\)
\(=-31\cdot\left(47+52+1\right)\)
\(=-31\cdot100=-3100\)
Bài 2:
1) Ta có: \(-17-\left(2x-5\right)=-6\)
\(\Leftrightarrow-17-2x+5+6=0\)
\(\Leftrightarrow-2x-6=0\)
\(\Leftrightarrow-2x=6\)
hay x=-3
Vậy: x=-3
2) Ta có: \(10-2\left(4-3x\right)=-4\)
\(\Leftrightarrow10-8+6x+4=0\)
\(\Leftrightarrow6x+6=0\)
\(\Leftrightarrow6x=-6\)
hay x=-1
Vậy: x=-1
3) Ta có: \(-12+3\left(-x+7\right)=-18\)
\(\Leftrightarrow-12-3x+21+18=0\)
\(\Leftrightarrow-3x+27=0\)
\(\Leftrightarrow-3x=-27\)
hay x=9
Vậy: x=9
4) Ta có: \(-45:\left[5\cdot\left(-3-2x\right)\right]=3\)
\(\Leftrightarrow5\cdot\left(-3-2x\right)=-15\)
\(\Leftrightarrow-2x-3=-3\)
\(\Leftrightarrow-2x=0\)
hay x=0
Vậy: x=0
5) Ta có: x(x+3)=0
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x+3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-3\end{matrix}\right.\)
Vậy: \(x\in\left\{0;-3\right\}\)
6) Ta có: (x-2)(x+4)=0
\(\Leftrightarrow\left[{}\begin{matrix}x-2=0\\x+4=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2\\x=-4\end{matrix}\right.\)
Vậy: \(x\in\left\{2;-4\right\}\)
7) Ta có: \(x\left(x+1\right)\left(x-3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x+1=0\\x-3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-1\\x=3\end{matrix}\right.\)
Vậy: \(x\in\left\{0;-1;3\right\}\)
Bài 1:
1) Ta có: (−12)+6⋅(−3)(−12)+6⋅(−3)
=−12−18=−12−18
=-30
2) Ta có: (36−2020)+(2019−136)−27(36−2020)+(2019−136)−27
=36−2020+2019−136−27=36−2020+2019−136−27
=1−100−27=1−100−27
=−126
Tớ chcs cậu học thật giỏi nha !
tìm x
67 - 3x = 31
=> 3x = 36
=> x = 12 ,
18 + 3x =24
=> 3x = 6
=> x = 2
( x - 36 ) : 18 = 12
=> x - 36 = 216
=> x = 252
, ( x + 74 ) - 318 = 200
=> x + 74 = 518
=> x = 444
3636 : ( 12x - 91 ) = 36 ,
=> 12x - 91 = 101
=> 12x = 192
=> x = 16
( x : 23 + 45 ) x 67 = 8911
=> x : 23 + 45 = 133
=> x : 23 = 88
=> x = 2024
Tìm x
67 - 3x = 31
=> 3x = 67 - 31
=> 3x = 46
=> x = 46/3
18 + 3x = 24
=> 3x = 24 - 18
=> 3x = 6
=> x = 2
(x - 36) : 18 = 12
x - 36 = 12.18
x - 36 = 216
x = 216 + 36
x = 252
(x + 74) - 318 = 200
x + 74 = 200 + 318
x + 74 = 518
x = 518 - 74
x = 444
3636 : (12x - 91) = 36
12x - 91 = 3636 : 36
12x - 91 = 101
12x = 101 + 91
12x = 192
x = 16
(x : 23 + 45) x 67 = 8911
x : 23 + 45 = 8911 : 67
x : 23 + 45 = 133
x : 23 = 133 + 45
x : 23 = 178
x = 4094
a. (x+74)-318=200
=>x+74=200+318
x+74=518
x =518-74
x =444
b. 3636:(12.x-91)=36
=> 12.x-91=3636:36
12.x-91=101
12.x =101+91
12.x =192
x =192:12
x =16
c. (x:23+45).67=8911
=>x:23+45=8911:67
x:23+45=133
x:23 =133-45
x:23 =88
x =88.23
x =2024
318-74=244
200+318=518
mình chỉ biết giải đến đấy thôi đừng giận mình nhé
a) 23 - (x + 74)= 36 + (-75)
23- ( x+74) = -39
x+74= 23 -( -39)
x+64= 62
x= 62-64
x= -2
Vậy...
2lx+9l - 68 = -24
2 |x+9| = -24+68
2| x+9|=44
|x+9| = 44:2
|x+9|= 22
TH1: x+9= -22
x= -22-9
x= -31
TH2: x+9=22
x= 22-9
x= 13
Vậy....