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a) 7x - 35 = 0
<=> 7x = 0 + 35
<=> 7x = 35
<=> x = 5
b) 4x - x - 18 = 0
<=> 3x - 18 = 0
<=> 3x = 0 + 18
<=> 3x = 18
<=> x = 5
c) x - 6 = 8 - x
<=> x - 6 + x = 8
<=> 2x - 6 = 8
<=> 2x = 8 + 6
<=> 2x = 14
<=> x = 7
d) 48 - 5x = 39 - 2x
<=> 48 - 5x + 2x = 39
<=> 48 - 3x = 39
<=> -3x = 39 - 48
<=> -3x = -9
<=> x = 3
a) 4 ( x + 5 )( x + 6 )( x + 10 )( x + 12 ) = 3x2
Do x = 0 không là nghiệm pt nên chia 2 vế pt cho \(x^2\ne0\), ta được :
\(\frac{4}{x^2}\left(x^2+60+17x\right)\left(x^2+60+16x\right)=3\)
\(\Leftrightarrow4\left(x+\frac{60}{x}+17\right)\left(x+\frac{60}{x}+16\right)=3\)
Đến đây ta đặt \(x+\frac{60}{x}+16=t\left(1\right)\)
Ta được :
\(4t\left(t+1\right)=3\Leftrightarrow4t^2+4t-3=0\Leftrightarrow\left(2t+3\right)\left(2t-1\right)=0\)
Từ đó ta lắp vào ( 1 ) tính được x
\(\Leftrightarrow\frac{5\left(x+5\right)-3\left(x-3\right)}{15}=\frac{5\left(x+5\right)-3\left(x-3\right)}{\left(x-3\right)\left(x+5\right)}\)
\(\Leftrightarrow\frac{2x+34}{15}=\frac{2x+34}{x^2+2x-15}\Leftrightarrow\orbr{\begin{cases}2x+34=0\\x^2+2x-15=15\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=-17\\x^2+2x-30=0\end{cases}}\)
Từ đó tìm được \(S=\left\{-17;\sqrt{31}-1;-\sqrt{31}-1\right\}\)
\(\frac{5x-3}{6}-\frac{7x-1}{4}-\frac{4x+2}{7}+5=0\)
<=> \(\frac{14\left(5x-3\right)-21\left(7x-1\right)-12\left(4x+2\right)+420}{84}=0\)
<=> 70x - 42 - 147x + 21 - 48x -24 + 420 = 0
<=> -125x + 375 = 0
<=> -125x = -375
<=> x = 3
Vậy S = {3}
\(\frac{3\left(2x+1\right)}{4}-5-\frac{3x+2}{10}=\frac{2\left(3x-1\right)}{5}\)
<=> \(\frac{15\left(2x+1\right)-100-2\left(3x+2\right)}{20}=\frac{8\left(3x-1\right)}{20}\)
<=> 30x + 15 - 100 - 6x - 4 = 24x - 8
<=> 24x - 24x = -8 + 89
<=> 0x = 81
=> pt vô nghiệm
a) <=> \(6x^2-5x+3-2x+3x\left(3-2x\right)=0\)
<=> \(6x^2-5x+3-2x+9x-6x^2=0\)
<=> \(2x+3=0\)
<=> \(x=\frac{-3}{2}\)
b) <=> \(10\left(x-4\right)-2\left(3+2x\right)=20x+4\left(1-x\right)\)
<=> \(10x-40-6-4x=20x+4-4x\)
<=> \(6x-46-16x-4=0\)
<=> \(-10x-50=0\)
<=> \(-10\left(x+5\right)=0\)
<=> \(x+5=0\)
<=> \(x=-5\)
c) <=> \(8x+3\left(3x-5\right)=18\left(2x-1\right)-14\)
<=> \(8x+9x-15=36x-18-14\)
<=> \(8x+9x-36x=+15-18-14\)
<=> \(-19x=-14\)
<=> \(x=\frac{14}{19}\)
d) <=>\(2\left(6x+5\right)-10x-3=8x+2\left(2x+1\right)\)
<=> \(12x+10-10x-3=8x+4x+2\)
<=> \(2x-7=12x+2\)
<=> \(2x-12x=7+2\)
<=> \(-10x=9\)
<=> \(x=\frac{-9}{10}\)
e) <=> \(x^2-16-6x+4=\left(x-4\right)^2\)
<=> \(x^2-6x-12-\left(x-4^2\right)=0\)
<=> \(x^2-6x-12-\left(x^2-8x+16\right)=0\)
<=> \(x^2-6x-12-x^2+8x-16=0\)
<=> \(2x-28=0\)
<=> \(2\left(x-14\right)=0\)
<=> x-14=0
<=> x=14
a) \(\frac{4-3x}{5}-\frac{4-x}{10}=\frac{x+2}{2}\)
\(\frac{8-6x-4+x}{10}=\frac{5x+10}{10}\)
\(4-5x=5x+10\)
\(4-5x-5x-10=0\)
\(-6-10x=0\)
\(\Rightarrow x=\frac{-3}{5}\)
Vậy....
\(\frac{4-3x}{5}-\frac{4-x}{10}=\frac{x+2}{2}\)
\(\Leftrightarrow\)\(\frac{2.\left(4-3x\right)}{10}-\frac{4-x}{10}=\frac{5.\left(x+2\right)}{10}\)
\(\Rightarrow\) 2.( 4 - 3x ) - 4 + x = 5.( x + 2 )
\(\Leftrightarrow\)8 - 6x - 4+ x = 5x + `10
\(\Leftrightarrow\)-6x + x - 5x = -8 + 4 + 10
\(\Leftrightarrow\) -10x = 6
\(\Leftrightarrow\)\(x=\frac{-3}{5}\)
Vậy phương trình có nghiệm là: \(x=\frac{-3}{5}\)
b ) \(\frac{x+1}{2009}+\frac{x+2}{2008}=\frac{x+2007}{3}+\frac{x+2006}{4}\)
\(\Leftrightarrow\) \(\frac{x+1}{2009}+1+\frac{x+2}{2008}+1\)\(=\frac{x+2007}{3}+1+\frac{x+2006}{4}+1\)
\(\Leftrightarrow\)\(\frac{x+1}{2009}+\frac{2009}{2009}+\frac{x+2}{2008}+\frac{2008}{2008}\)\(=\frac{x+2007}{3}+\frac{3}{3}+\frac{x+2006}{4}+\frac{4}{4}\)
\(\Leftrightarrow\)\(\frac{x+2010}{2009}+\frac{x+2010}{2008}=\frac{x+2010}{3}+\frac{x+2006}{4}\)
\(\Leftrightarrow\)\(\frac{x+2010}{2009}+\frac{x+2010}{2008}-\frac{x+2010}{3}-\frac{x+2010}{4}=0\)
\(\Leftrightarrow\)\(\left(x+2010\right).\left(\frac{1}{2009}+\frac{1}{2008}-\frac{1}{3}-\frac{1}{4}\right)=0\)
\(\Leftrightarrow\)\(x+2010=0\) ( Vì \(\frac{1}{2009}+\frac{1}{2008}-\frac{1}{3}-\frac{1}{4}\ne0\))
\(\Leftrightarrow\) \(x=-2010\)
Vậy phương trình có nghiệm là: x = -2010
a) \(x^3-2x^2-5x+6=0\)
\(x^3-x^2-x^2+x-6x+6=0\)
\(x^2\left(x-1\right)-x\left(x-1\right)-6\left(x-1\right)=0\)
\(\left(x-1\right)\left(x^2-x-6\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x-1=0\\x^2-x-6=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=1\\x^2-2x+3x-6=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=1\\\left(x+3\right)\left(x-2\right)=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=1\\x=\left\{2;-3\right\}\end{cases}}\)
\(a,x^3-2x^2-5x+6=0\)
\(\Leftrightarrow\left(x^3-x^2\right)-\left(x^2-x\right)-\left(6x-6\right)=0\)
\(\Leftrightarrow x^2\left(x-1\right)-x\left(x-1\right)-6\left(x-1\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(x^2-x-6\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left[\left(x^2-3x\right)+\left(2x-6\right)\right]=0\)
\(\Leftrightarrow\left(x-1\right)\left[x\left(x-3\right)+2\left(x-3\right)\right]=0\)
\(\Leftrightarrow\left(x-1\right)\left(x+2\right)\left(x-3\right)=0\)
\(\Leftrightarrow x-1=0\left(h\right)x+2=0\left(h\right)x-3=0\)
\(\Leftrightarrow x=1\left(h\right)x=-2\left(h\right)x=3\)
Vậy \(x\in\left\{-2;1;3\right\}\)
P/S: (h) là hoặc nhé
\(\frac{x+4}{5}+\frac{3x+2}{10}< \frac{x-1}{3}\)
\(\Leftrightarrow\frac{6\left(x+4\right)}{30}+\frac{3\left(3x+2\right)}{30}< \frac{10\left(x-1\right)}{30}\)
\(\Leftrightarrow6x+24+9x+6< 10x-10\)
\(\Leftrightarrow5x+40< 0\)
\(\Leftrightarrow x< -8\)
Tự biểu diễn nha bạn
\(\frac{x+4}{5}+\frac{3x+2}{10}< \frac{x-1}{3}\)
\(\Rightarrow\frac{6\left(x+4\right)}{30}+\frac{3\left(3x+2\right)}{30}< \frac{10\left(x-1\right)}{30}\)
\(\Rightarrow6x+24+9x+6< 10x-10\)
\(5x< -40\)
\(\Rightarrow x< -8\)
\(\frac{{3x - 2}}{5} + \frac{3}{2} = \frac{{4 - x}}{{10}}\)
\(\frac{{\left( {3x - 2} \right).2}}{{5.2}} + \frac{{3.5}}{{2.5}} = \frac{{4 - x}}{{10}}\)
\(\frac{{6x - 4}}{{10}} + \frac{{15}}{{10}} = \frac{{4 - x}}{{10}}\)
\(6x - 4 + 15 = 4 - x\)
\(6x + x = 4 + 4 - 15\)
\(7x = - 15\)
\(x = \left( { - 15} \right):7\)
\(x = \frac{{ - 15}}{7}\)
Vậy phương trình có nghiệm là \(x = \frac{{ - 15}}{7}\).