Cho mình hỏi bài này:
Tìm x biết
264+12 x=1800
(x+73):19=321
2x+3x+4x=18
10<2 x <20
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264+12x=1800
12x=1536
x=128
(x+73):19=321
x+73=6099
x=6026
2x+3x+4x=18
9x=18
x=2
10<2x<20
=>5<x<10
x=6,7,8,9
\(264+12x=1800\)
\(\Leftrightarrow12x=1536\)
\(\Leftrightarrow x=128\)
==============
\(\left(x+73\right):19=321\)
\(\Leftrightarrow x+73=6099\)
\(\Leftrightarrow x=6026\)
===============
\(2x+3x+4x=18\)
\(\Leftrightarrow x.\left(2+3+4\right)=18\)
\(\Leftrightarrow x.9=18\)
\(\Leftrightarrow x=2\)
================
\(10< 2x< 20\)
..................................
\(2x=12\Leftrightarrow x=6\)
\(2x=14\Leftrightarrow x=7\)
\(2x=16\Leftrightarrow x=8\)
\(2x=18\Leftrightarrow x=9\)
\(x\in\left\{6;7;8;9\right\}\)
264 + 2x = 1800
2x = 1800 - 246
2x = 1554
x = 1554 : 2
x = 777
( x + 73 ) : 19 = 321
x + 73 = 321 x 19
x + 73 = 6099
x = 6099 - 73
x = 6026
2x + 3x + 4x = 18
x = 2
Câu cuối của bài 1 và bài 2 mình ko biết ~
a) \(\text{264 + 12x = 1800}\)
\(\Rightarrow12x=1800-264\)
\(\Rightarrow12x=1536\)
\(\Rightarrow x=1536:12\)
\(\Rightarrow x=128\)
b) \(\text{( x + 73 ) : 19 = 321}\Rightarrow x+73=6099\Rightarrow x=6026\)
c) 2x + 3x + 4x = 18
=> x.(2+3+4)=18
=> x.9 = 18
=> x=18 : 2
=> x= 2
\(1,\Leftrightarrow7x=42\Leftrightarrow x=6\\ 2,\Leftrightarrow36-4x=4\Leftrightarrow4x=32\Leftrightarrow x=8\\ 3,\Leftrightarrow3x=35\Leftrightarrow x=\dfrac{35}{3}\\ 4,\Leftrightarrow x-12=144\Leftrightarrow x=156\\ 5,\Leftrightarrow x-14=16\Leftrightarrow x=30\\ 6,\Leftrightarrow3x-24=\dfrac{148}{73}\Leftrightarrow3x=\dfrac{1900}{73}\Leftrightarrow x=\dfrac{1900}{219}\\ 7,\Leftrightarrow33+x=45\Leftrightarrow x=12\\ 8,Sai.đề\\ 9,\Leftrightarrow\left(x+9\right):2=39\Leftrightarrow x+9=78\Leftrightarrow x=69\\ 11,\Leftrightarrow2\left(x+7\right)=38\Leftrightarrow x+7=19\Leftrightarrow x=12\\ 13,\Leftrightarrow2\left(x-51\right)=66\Leftrightarrow x-51=33\Leftrightarrow x=84\)
\(15,\Leftrightarrow x-19=9\Leftrightarrow x=28\\ 17,\Leftrightarrow\left(x-3\right):2=48\Leftrightarrow x-3=96\Leftrightarrow x=99\\ 19,\Leftrightarrow0x=46\Leftrightarrow x\in\varnothing\\ 8,Sai.đề\\ 14,\Leftrightarrow2x=209\Leftrightarrow x=\dfrac{209}{2}\\ 16,\Leftrightarrow2x+6=157\Leftrightarrow2x=151\Leftrightarrow x=\dfrac{151}{2}\\ 18,\Leftrightarrow5\left(x+4\right)=100\Leftrightarrow x+4=20\Leftrightarrow x=16\\ 20,\Leftrightarrow\left(3x-5\right)^3=27=3^3\Leftrightarrow3x-5=3\Leftrightarrow x=\dfrac{8}{3}\)
1
a, -114
b, -1000
c, 87
d, 164
e, 981
2
a, x=14
b, x E {-32,2}
c, đề sai
d, 262
e, -3
g, đề sai
h, -3
Ta có : 3x + 8 = 3(x - 1) + 11
Do x - 1 \(⋮\)x - 1 => 3(x - 1) \(⋮\)x - 1
Để 3x + 8 \(⋮\)x - 1 thì 11 \(⋮\)x - 1 => x - 1 \(\in\)Ư(11) = {1; 11; -1; -11}
Lập bảng :
3x + 8 | 1 | 11 | -1 | -11 |
x | -7/3 | 1 | -3 | -19/3 |
Vậy ...
a) \(58+7x=100\)
\(=>7x=100-58\)
\(=>7x=42\)
\(=>x=42:7\)
\(=>x=6\)
b) \(3x-7=28\)
\(=>3x=28+7\)
\(=>3x=35\)
\(=>x=35:3\)
\(=>x=\dfrac{35}{3}\)
c) \(x-56:4=16\)
\(=>x-14=16\)
\(=>x=16+14\)
\(=>x=30\)
d) \(101+\left(36-4x\right)=105\)
\(=>36-4x=105-101\)
\(=>36-4x=4\)
\(=>4x=36-4\)
\(=>4x=32\)
\(=>x=32:4\)
\(=>x=8\)
e) \(\left(x-12\right):12=12\)
\(=>x-12=12.12\)
\(=>x-12=144\)
\(=>x=144-12\)
\(=>x=132\)
f) \(\left(3x-2^4\right).7^3=2.7^4\)
\(=>3x-2^4=2.7^4:7^3\)
\(=>3x-16=2.7=14\)
\(=>3x=14+16\)
\(=>3x=30\)
\(=>x=30:3\)
\(=>x=10\)
i) \(\left(10+2x\right).4^{2011}=4^{2013}\)
\(=>10+2x=4^{2013}:4^{2011}\)
\(=>10+2x=4^2=16\)
\(=>2x=16-10\)
\(=>2x=6\)
\(=>x=6:2\)
\(=>x=3\)
\(#WendyDang\)
a: \(x^3-4x^2-x+4=0\)
=>\(\left(x^3-4x^2\right)-\left(x-4\right)=0\)
=>\(x^2\left(x-4\right)-\left(x-4\right)=0\)
=>\(\left(x-4\right)\left(x^2-1\right)=0\)
=>\(\left[{}\begin{matrix}x-4=0\\x^2-1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=4\\x^2=1\end{matrix}\right.\Leftrightarrow x\in\left\{2;1;-1\right\}\)
b: Sửa đề: \(x^3+3x^2+3x+1=0\)
=>\(x^3+3\cdot x^2\cdot1+3\cdot x\cdot1^2+1^3=0\)
=>\(\left(x+1\right)^3=0\)
=>x+1=0
=>x=-1
c: \(x^3+3x^2-4x-12=0\)
=>\(\left(x^3+3x^2\right)-\left(4x+12\right)=0\)
=>\(x^2\cdot\left(x+3\right)-4\left(x+3\right)=0\)
=>\(\left(x+3\right)\left(x^2-4\right)=0\)
=>\(\left(x+3\right)\left(x-2\right)\left(x+2\right)=0\)
=>\(\left[{}\begin{matrix}x+3=0\\x-2=0\\x+2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-3\\x=2\\x=-2\end{matrix}\right.\)
d: \(\left(x-2\right)^2-4x+8=0\)
=>\(\left(x-2\right)^2-\left(4x-8\right)=0\)
=>\(\left(x-2\right)^2-4\left(x-2\right)=0\)
=>\(\left(x-2\right)\left(x-2-4\right)=0\)
=>(x-2)(x-6)=0
=>\(\left[{}\begin{matrix}x-2=0\\x-6=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2\\x=6\end{matrix}\right.\)
bn hỏi 1 lần thôi đừng đăng nhiều chật lắm
12x = 1800 - 264
12x = 1536
x = 1536 : 12
x = 128
( x + 73 ) : 19 = 321
( x + 73 ) = 321 x 19
x + 73 = 6099
x = 6099 - 73
x = 6026
2x + 3x + 4x = 18
x . ( 2 + 3 + 4 ) = 18
x . 9 = 18
x = 18 : 9
x = 2
10 < 2x < 20
x = 6 ; 7 ; 8 ; 9