3x-1+3x+2=140
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a) \(288-\left(3x-359\right)=140\)
\(3x-359=288-140\)
\(3x-359=148\)
\(3x=507\)
\(x=169\)
vay \(x=169\)
b) \(\left(3x-2\right)^2=49\)
\(\left(3x-2\right)^2=7^2\)
\(\Rightarrow3x-2=7\)
\(\Rightarrow3x=9\)
\(\Rightarrow x=3\)
vay \(x=3\)
288-(3x-359)=140
3x-359=288-140
3x=148+359
x=507:3
x=169
Vay x=169
TA CÓ
140=20 X 7 =....
BẠN TỰ THỬ VÀO MÀ TÍNH X
MK CHỈ GỢI Ý ĐẾN ĐÂY THÔI
Bài 1:
a) Ta có: \(82-7\left(3x-4\right)=47\)
\(\Leftrightarrow82-21x+28-47=0\)
\(\Leftrightarrow-21x+63=0\)
\(\Leftrightarrow-21x=-63\)
hay x=3(nhận)
Vậy: x=3
b) Ta có: \(97+4\left(5x-7\right)=129\)
\(\Leftrightarrow97+20x-28-129=0\)
\(\Leftrightarrow20x-60=0\)
\(\Leftrightarrow20x=60\)
hay x=3(nhận)
Vậy: x=3
c) Ta có: \(\left(7x-13\right)\cdot27-12=15\)
\(\Leftrightarrow189x-351-12-15=0\)
\(\Leftrightarrow189x-378=0\)
\(\Leftrightarrow189x=378\)
hay x=2(nhận)
Vậy: x=2
d) Ta có: \(\left(2x+3\right)\cdot13+23=140\)
\(\Leftrightarrow26x+39+23-140=0\)
\(\Leftrightarrow26x-78=0\)
\(\Leftrightarrow26x=78\)
hay x=3(nhận)
Vậy: x=3
đ) Ta có: \(52x+8x-5x=70\)
\(\Leftrightarrow55x=70\)
\(\Leftrightarrow x=\frac{70}{55}\)(loại)
Vậy: x∈∅
e) Ta có: \(19x-3x-x=60\)
\(\Leftrightarrow15x=60\)
hay x=4(nhận)
Vậy: x=4
g) Ta có: \(7\left(3x+1\right)-5\left(3x+1\right)=74\)
\(\Leftrightarrow2\left(3x+1\right)=74\)
\(\Leftrightarrow3x+1=37\)
\(\Leftrightarrow3x=36\)
hay x=12(nhận)
Vậy: x=12
h) Ta có: \(5\left(3x-1\right)+7\left(3x-1\right)=96\)
\(\Leftrightarrow12\left(3x-1\right)=96\)
\(\Leftrightarrow3x-1=8\)
\(\Leftrightarrow3x=9\)
hay x=3(nhận)
Vậy: x=3
c: 90\(⋮\)x-2
=>\(x-2\in\){1;-1;2;-2;3;-3;5;-5;6;-6;9;-9;10;-10;15;-15;18;-18;30;-30;45;-45;90;-90}
=>x\(\in\){3;1;4;0;5;-1;7;-3;8;-4;11;-7;12;-8;17;-13;20;-16;32;-28;47;-43;92;-88}
mà 10<=x<=90
nên \(x\in\left\{11;12;17;20;32;47\right\}\)
d: \(x⋮12\)
=>\(x\in\left\{0;12;24;36;48;60;72;...\right\}\)
mà 30<=x<=60
nên \(x\in\left\{36;48;60\right\}\)
a: x-140:35=270
=>x-4=270
=>x=270+4=274
b: \(\left(3x-1\right)^2-3^2=4^2\)
=>(3x-1)2-9=16
=>\(\left(3x-1\right)^2=25\)
=>\(\left[{}\begin{matrix}3x-1=5\\3x-1=-5\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}3x=6\\3x=-4\end{matrix}\right.\)
=>\(\left[{}\begin{matrix}x=2\\x=-\dfrac{4}{3}\end{matrix}\right.\)
\(a̸\)
\(\frac{3}{5}-\frac{1}{2}.x=\frac{1}{4}\)
\(\frac{1}{2}.x=\frac{3}{5}-\frac{1}{4}\)
\(\frac{1}{2}.x=\frac{7}{20}\)
\(\Rightarrow\frac{7}{10}\)
\(b̸\)
\(11,3+2\left[x-\frac{1}{3}\right]=\frac{25}{6}\)
\(2\left[x-\frac{1}{3}\right]=\frac{25}{6}-11,3\)
\(2\left[x-\frac{1}{3}\right]=\frac{-107}{15}\)
\(x-\frac{1}{3}=\frac{-107}{15}:2\)
\(x-\frac{1}{3}=\frac{-107}{30}\)
\(x=\frac{-107}{30}+\frac{1}{3}\)
\(x=\frac{-97}{30}\)
\(a)\frac{3}{5}-\frac{1}{2}x=\frac{1}{4}\)
\(\implies\frac{1}{2}x=\frac{3}{5}-\frac{1}{4}\)
\(\implies\frac{1}{2}x=\frac{7}{20}\)
\(\implies x=\frac{7}{20}:\frac{1}{2}\)
\(\implies x=\frac{7}{10}\)
Vậy...
\(b) 11,3+2(x-\frac{1}{3})=\frac{25}{6}\)
\(\implies \frac{113}{10}+2x-2.\frac{1}{3}=\frac{25}{6}\)
\(\implies \frac{113}{10}+2x-\frac{2}{3}=\frac{25}{6}\)
\(\implies \frac{113}{10}+2x=\frac{25}{6}+\frac{2}{3}\)
\(\implies \frac{113}{10}+2x=\frac{29}{6}\)
\(\implies 2x=\frac{29}{6}-\frac{113}{10}\)
\(\implies 2x=\frac{-97}{15}\)
\(\implies x=\frac{-97}{30}\)
Vậy..
\(c)5x-435+2x+140+3x=565\)
\(\implies (5x+2x+3x)+(-435+140)=565\)
\(\implies 10x+(-295)=565\)
\(\implies 10x=565-(-295)\)
\(\implies 10x=860\)
\(\implies x=86\)
Vậy...
~ hok tốt a~
a: =>31-x=60
=>x=-29
b: =>(x-140):35=280-270=10
=>x-140=350
=>x=490
c: =>(1900-2x):35=48
=>1900-2x=1680
=>2x=220
=>x=110
d: =>\(2^{2x-1}=2^9\cdot2=2^{11}\)
=>2x-1=11
=>x=6
e: =>(x+2)^5=4^5
=>x+2=4
=>x=2
f: =>3x-4=0 hoặc x-1=0
=>x=4/3 hoặc x=1
g: =>(2x-1)^2=49
=>2x-1=7 hoặc 2x-1=-7
=>x=-3 hoặc x=4
h: =>x(x+1)/2=78
=>x(x+1)=156
=>x=12
Bài làm :
\(1\text{)}...\Leftrightarrow\orbr{\begin{cases}\left(1+3x\right)^4=4^4\Leftrightarrow1+3x=4\Leftrightarrow3x=3\Leftrightarrow x=1\\\left(1+3x\right)^4=\left(-4\right)^4\Leftrightarrow1+3x=-4\Leftrightarrow3x=-5\Leftrightarrow x=-\frac{5}{3}\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=1\\x=-\frac{5}{3}\end{cases}}\)
\(2\text{)}...\Leftrightarrow720\div\left(x-140\right)=-5\Leftrightarrow x-140=-144\Leftrightarrow x=-4\)
\(3\text{)}...\Leftrightarrow\left(2^4\right)^x.\left(2^2\right)^3=2^9\Leftrightarrow2^{4x}.2^6=2^9\Leftrightarrow2^{4x}=2^3\Leftrightarrow4x=3\Leftrightarrow x=\frac{3}{4}\)
\(4\text{)}...\Leftrightarrow\orbr{\begin{cases}\left(2x-1\right)^4=3^4\Leftrightarrow2x-1=3\Leftrightarrow2x=4\Leftrightarrow x=2\\\left(2x-1\right)^4=\left(-3\right)^4\Leftrightarrow2x-1=-3\Leftrightarrow2x=-2\Leftrightarrow x=-1\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=2\\x=-1\end{cases}}\)
a) (x - 140) : 7 = 33 - 23 . 3
(x - 140) : 7 = 27 - 8 . 3 = 27 - 24 = 3
x - 140 = 3 x 7 = 21
x = 21 + 140 = 161
b) x3 . x2 = 28 : 23
x5 = 25
=> x = 2
c) (x + 2) . ( x - 4) = 0
x = -2 hoặc 4
d) 3x-3 - 32 = 2 . 32 =
3x-3 - 9 = 2 . 9 = 18
3x-3 = 18 + 9 = 27
3x-3 = 33
=> x - 3 = 3
x = 3 + 3 = 6