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KH
22 tháng 9 2018
* Trả lời:
\(\left(1\right)\) \(-3\left(1-2x\right)-4\left(1+3x\right)=-5x+5\)
\(\Leftrightarrow-3+6x-4-12x=-5x+5\)
\(\Leftrightarrow6x-12x+5x=3+4+5\)
\(\Leftrightarrow x=12\)
\(\left(2\right)\) \(3\left(2x-5\right)-6\left(1-4x\right)=-3x+7\)
\(\Leftrightarrow6x-15-6+24x=-3x+7\)
\(\Leftrightarrow6x+24x+3x=15+6+7\)
\(\Leftrightarrow33x=28\)
\(\Leftrightarrow x=\dfrac{28}{33}\)
\(\left(3\right)\) \(\left(1-3x\right)-2\left(3x-6\right)=-4x-5\)
\(\Leftrightarrow1-3x-6x+12=-4x-5\)
\(\Leftrightarrow-3x-6x+4x=-1-12-5\)
\(\Leftrightarrow-5x=-18\)
\(\Leftrightarrow x=\dfrac{18}{5}\)
\(\left(4\right)\) \(x\left(4x-3\right)-2x\left(2x-1\right)=5x-7\)
\(\Leftrightarrow4x^2-3x-4x^2+2x=5x-7\)
\(\Leftrightarrow-x-5x=-7\)
\(\Leftrightarrow-6x=-7\)
\(\Leftrightarrow x=\dfrac{7}{6}\)
\(\left(5\right)\) \(3x\left(2x-1\right)-6x\left(x+2\right)=-3x+4\)
\(\Leftrightarrow6x^2-3x-6x^2-12x=-3x+4\)
\(\Leftrightarrow-15x+3x=4\)
\(\Leftrightarrow-12x=4\)
\(\Leftrightarrow x=-\dfrac{1}{3}\)
TN
2
6 tháng 7 2016
4 ) \(\left|3-2x\right|=\frac{4}{3}\)
+) \(3-2x=\frac{4}{3}\)
\(2x=3-\frac{4}{3}\)
\(2x=\frac{5}{3}\)
\(x=\frac{5}{3}:2\)
\(x=\frac{5}{3}.\frac{1}{2}\)
\(x=\frac{10}{3}\)
+) \(3-2x=-\frac{4}{3}\)
\(2x=3--\frac{4}{3}\)
\(2x=\frac{13}{3}\)
\(x=\frac{13}{3}:2\)
\(x=\frac{13}{3}.\frac{1}{2}\)
\(x=\frac{26}{3}\)
Rồi tiếp tục giải đi mk cũng giống @Đinh Tuấn Việt
17 tháng 9 2023
a) \(({x^2} + 2x + 3) + (3{x^2} - 5x + 1) = ({x^2} + 3{x^2}) + (2x - 5x) + (3 + 1) = 4{x^2} - 3x + 4\);
b) \(\begin{array}{l}(4{x^3} - 2{x^2} - 6) - ({x^3} - 7{x^2} + x - 5) = 4{x^3} - 2{x^2} - 6 - {x^3} + 7{x^2} - x + 5\\ = (4{x^3} - {x^3}) + ( - 2{x^2} + 7{x^2}) - x + ( - 6 + 5) = 3{x^3} + 5{x^2} - x - 1\end{array}\);
c) \(\begin{array}{l} - 3{x^2}(6{x^2} - 8x + 1) = - 3{x^2}.6{x^2} - - 3{x^2}.8x + - 3{x^2}.1\\ = - 18{x^{2 + 2}} + 24{x^{2 + 1}} - 3{x^2} = - 18{x^4} + 24{x^3} - 3{x^2}\end{array}\);
d) \(\begin{array}{l}(4{x^2} + 2x + 1)(2x - 1) = (4{x^2} + 2x + 1).2x - (4{x^2} + 2x + 1).1 = 4{x^2}.2x + 2x.2x + 1.2x - 4{x^2} - 2x - 1\\ = 8{x^{2 + 1}} + 4{x^{1 + 1}} + 2x - 4{x^2} - 2x - 1 = 8{x^3} + 4{x^2} + 2x - 4{x^2} - 2x - 1 = 8{x^3} - 1\end{array}\);
e) \(\begin{array}{l}({x^6} - 2{x^4} + {x^2}):( - 2{x^2}) = {x^6}:( - 2{x^2}) - 2{x^4}:( - 2{x^2}) + {x^2}:( - 2{x^2})\\ = - \dfrac{1}{2}{x^{6 - 2}} + {x^{4 - 2}} - \dfrac{1}{2}{x^{2 - 2}} = - \dfrac{1}{2}{x^4} + {x^2} - \dfrac{1}{2}.\end{array}\);
g)
\(({x^5} - {x^4} - 2{x^3}):({x^2} + x)=x^3-2x^2\)
Q
1
31 tháng 10 2015
a,(5x-1)6=36
5x-1=3
x=4/5
b,(2x+1)3=0,13
2x+1=0,1
x=-0,45
c,(2x-3)4=(2x-3)4(2x-3)2
(2x-3)2=0
2x-3=0
x=3/2
d,(2x+1)5=(2x+1)5(2x+1)2005
(2x+1)2005=0
2x+1=0
x=-1/2
PD
3
7 tháng 9 2016
a)\(\orbr{\begin{cases}5x-1=3\\5x-1=-3\end{cases}}\Leftrightarrow\orbr{\begin{cases}5x=4\\5x=-2\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=\frac{4}{5}\\x=\frac{-2}{5}\end{cases}}\)
b) 2x+1=-0,1 <=> 2x=-1,1=>x=-0,55
c) (2x-3)4 .[1-(2x-3)2 ]=0
do (2x-3)4 lớn hơn 0 nên 1-(2x-3)2=0=>(2x-3)2=1=>2x-3=1=>2x=4=>x=2
d) tương tự câu c)
25 tháng 12 2019
\(a)\frac{11}{4}-2x=\frac{-1}{2}\)
\(2x=\frac{11}{4}-\left(\frac{-1}{2}\right)\)
\(2x=\frac{11}{4}+\frac{1}{2}\)
\(2x=\frac{11}{4}+\frac{2}{4}\)
\(2x=\frac{13}{4}\)
\(x=\frac{13}{4}:2\)
\(x=\frac{13}{8}\)
\(b)\left|\frac{3}{4}-\frac{1}{2x}\right| +\frac{1}{3}=\frac{5}{6}\)
\(\left|\frac{3}{4}-\frac{1}{2x}\right|=\frac{5}{6}-\frac{1}{3}\)
\(\left|\frac{3}{4}-\frac{1}{2x}\right|=\frac{5}{6}-\frac{2}{6}\)
\(\left|\frac{3}{4}-\frac{1}{2x}\right|=\frac{3}{6}\)
\(TH1:\)
\(\frac{3}{4}-\frac{1}{2x}=\frac{3}{6}\)
\(\frac{1}{2x}=\frac{3}{4}-\frac{3}{6}\)
\(\frac{1}{2x}=\frac{18}{24}-\frac{12}{24}\)
\(\frac{1}{2x}=\frac{6}{24}\)
\(\frac{1}{2x}=\frac{1}{4}\)
\(\Rightarrow2x=4\)
\(x=4:2\)
\(x=2\)
\(TH2:\)
\(\frac{3}{4}-\frac{1}{2x}=\frac{-3}{6}\)
\(\frac{1}{2x}=\frac{3}{4}-\left(\frac{-3}{6}\right)\)
\(\frac{1}{2x}=\frac{3}{4}+\frac{3}{6}\)
\(\frac{1}{2x}=\frac{18}{24}+\frac{12}{24}\)
\(\frac{1}{2x}=\frac{30}{24}\)
\(\frac{1}{2x}=\frac{5}{4}\)
\(\Rightarrow1:2x=5:4\)
\(1:2x=1,25\)
\(2x=1:1,25\)
\(2x=0,8\)
\(x=0,8:2\)
\(\)\(x=0,4\)
12 tháng 7 2021
Bài 1:
a) Ta có: \(\dfrac{17}{6}-x\left(x-\dfrac{7}{6}\right)=\dfrac{7}{4}\)
\(\Leftrightarrow\dfrac{17}{6}-x^2+\dfrac{7}{6}x-\dfrac{7}{4}=0\)
\(\Leftrightarrow-x^2+\dfrac{7}{6}x+\dfrac{13}{12}=0\)
\(\Leftrightarrow-12x^2+14x+13=0\)
\(\Delta=14^2-4\cdot\left(-12\right)\cdot13=196+624=820\)
Vì Δ>0 nên phương trình có hai nghiệm phân biệt là:
\(\left\{{}\begin{matrix}x_1=\dfrac{14-2\sqrt{205}}{-24}=\dfrac{-7+\sqrt{205}}{12}\\x_2=\dfrac{14+2\sqrt{2015}}{-24}=\dfrac{-7-\sqrt{205}}{12}\end{matrix}\right.\)
b) Ta có: \(\dfrac{3}{35}-\left(\dfrac{3}{5}-x\right)=\dfrac{2}{7}\)
\(\Leftrightarrow\dfrac{3}{5}-x=\dfrac{3}{35}-\dfrac{10}{35}=\dfrac{-7}{35}=\dfrac{-1}{5}\)
hay \(x=\dfrac{3}{5}-\dfrac{-1}{5}=\dfrac{3}{5}+\dfrac{1}{5}=\dfrac{4}{5}\)