a) (x-1)^3-x(x+1)^2=5x(2-x)-11(x+2)
ĐS: x=-7
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12 tháng 6 2019
a) \(2x\left(x-3\right)-x\left(2x+1\right)-3\left(x+5\right)=11\)
\(\Rightarrow2x^2-6x-2x^2-x-3x-15=11\)
\(\Rightarrow-10x=26\Rightarrow x=-2,6\)
Vậy ...........
b) \(x\left(x-1\right)-\left(x^2+3x-5\right)-2\left(x+3\right)=17\)
\(\Rightarrow x^2-x-x^2-3x+5-2x-6=17\)
\(\Rightarrow-6x=18\Rightarrow x=-3\)
c) \(5x\left(x-7\right)-\left(5x+1\right)x-\left(x+3\right)2=13\)
\(\Rightarrow5x^2-35x-5x^2-x-2x-6=13\)
\(\Rightarrow-38x=19\Rightarrow x=-\frac{1}{2}\)
d) \(\left(2x^2-3x+5\right)-2x\left(x-3\right)+\left(x-1\right)\left(-2\right)=10\)
\(\Rightarrow2x^2-3x+5-2x^2+6x-2x+2=10\)
\(\Rightarrow x=3\)
HV
1
13 tháng 1 2018
a, (x-1)^2 + (x+3)^2 = 2(x-2)(x+1) + 38
<=> x^2 -2x +1 + x^2 + 6x +9 = 2x^2 +2x -4x -4 +38
<=> x^2 -2x +x^2 +6x -2x^2 -2x +4x= -4 +38 -10
<=> 6x= 24
<=> x = 4
=> S={4}
b, 5(2x-3)-4(5x-7)= 19 -2(x+11)
<=> 10x -15 -20x +28 = 19-2x-22
<=> 10x -20x +2x = 19 -22 +15 -28
<=> -8x = -16
<=> x = 2
=> S={2}
19 tháng 6 2022
a: \(\Leftrightarrow x\cdot\dfrac{1}{4}+\dfrac{3}{4}=3-\dfrac{1}{2}x-\dfrac{1}{2}-\dfrac{1}{3}x-\dfrac{2}{3}\)
=>13/12x=13/12
hay x=1
b: \(\Leftrightarrow\dfrac{3x-11}{11}-\dfrac{x}{3}=\dfrac{3x-5}{7}-\dfrac{5x-3}{9}\)
\(\Leftrightarrow\dfrac{3}{11}x-1-\dfrac{1}{3}x=\dfrac{3}{7}x-\dfrac{5}{7}-\dfrac{5}{9}x+\dfrac{1}{3}\)
\(\Leftrightarrow x\cdot\dfrac{46}{693}=\dfrac{13}{21}\)
hay x=429/46
8 tháng 2 2022
a, \(\Rightarrow10x-4+6x=6+15-9x\Leftrightarrow7x=25\Leftrightarrow x=\dfrac{25}{7}\)
b, \(\Rightarrow2\left(3x^2+5x-2\right)-6x^2-3=33\Leftrightarrow10x-7=33\Leftrightarrow x=4\)
c, \(\Rightarrow12x-10x-4=21-9x\Leftrightarrow11x=25\Leftrightarrow x=\dfrac{25}{11}\)
d, \(\Rightarrow3x-3+2x-2-x+1=12\Leftrightarrow4x=16\Leftrightarrow x=4\)
TC
8 tháng 5 2022
a)\(=\dfrac{3}{3}+\dfrac{4}{3}=\dfrac{7}{3}\)
b)\(=\dfrac{5}{9}\times\dfrac{3}{2}=\dfrac{15}{18}=\dfrac{5}{6}\)
d)\(=\left(\dfrac{12}{8}-\dfrac{3}{8}\right)\times2=\dfrac{9}{8}\times2=\dfrac{18}{8}=\dfrac{9}{4}\)
c)\(=\dfrac{4}{3}-\dfrac{5}{6}=\dfrac{8}{6}-\dfrac{5}{6}=\dfrac{3}{6}=\dfrac{1}{2}\)
Q
8 tháng 5 2022
a) 1 + 4/3 = 7/3
b) 5/9 : 2/3 = 5/6
c ) 4/3 -1/3 x 5/2
= 1 x 5/2
= 5/2
d) ( 3/2 - 3/8) : 1/2
= 9/8 : 1/2
= 9/4
e) 15/16 : 3/8 x 3/4
= 5/2 x 3/4
= 15/8
f) 7/19 x 1/3 x 7/19 x 2/3
= 7/19 x (1/3 x 2/3)
= 7/19 x 2/9
= 14/171
g) 3/5 x 8/27 x 25/3
= 3/5 x 25/3 x 8/27
= 5 x 8/27
= 40/27
h) 1/5 + 4/11 + 4/5 + 7/11
= (1/5 + 4/5) + (4/11 + 7/11)
= 1 + 1
= 2
KV
18 tháng 4 2022
a) \(5x-3=7\)
\(\Leftrightarrow5x=7+3\)
\(\Leftrightarrow5x=10\)
\(\Leftrightarrow x=\dfrac{10}{5}\)
\(\Leftrightarrow x=2\)
Vậy \(S=\left\{2\right\}\)
b) \(\left(x+3\right)\left(x-4\right)=0\)
\(\Leftrightarrow x+3=0\) hoặc \(x-4=0\)
*) \(x+3=0\)
\(x=0-3\)
\(x=-3\)
*) \(x-4=0\)
\(x=0+4\)
\(x=4\)
Vậy \(S=\left\{-3;4\right\}\)
c) \(\left|x^2+2014\right|=1\)
\(\Leftrightarrow x^2+2014=1\) hoặc \(x^2+2014=-1\)
*) \(x^2+2014=1\)
\(\Leftrightarrow x^2=1-2014\)
\(\Leftrightarrow x^2=-2013\) (vô lý)
*) \(x^2+2014=-1\)
\(\Leftrightarrow x^2=-1-2014\)
\(\Leftrightarrow x^2=-2015\) (vô lý)
Vậy \(S=\varnothing\)
d) \(\dfrac{2}{x+1}-\dfrac{1}{x-3}=\dfrac{3x-11}{x^2-2x-3}\) (1)
ĐKXĐ: \(x\ne-1;x\ne3\)
\(\left(1\right)\Leftrightarrow2\left(x-3\right)-\left(x+1\right)=3x-11\)
\(\Leftrightarrow2x-6-x-1=3x-11\)
\(\Leftrightarrow-2x=-11+7\)
\(\Leftrightarrow-2x=-4\)
\(\Leftrightarrow x=2\) (nhận)
Vậy \(S=\left\{2\right\}\)
=>x^3-3x^2+3x-1-x(x^2+2x+1)=10x-5x^2-11x-22
=>x^3-3x^2+3x-1-x^3-2x^2-x=-5x^2-x-22
=>-5x^2+2x-1=-5x^2-x-22
=>2x-1=-x-22
=>3x=-21
=>x=-7