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a: =>\(\dfrac{5x-15+4x-8}{\left(x-2\right)\left(x-3\right)}=\dfrac{1}{x}\)
=>\(\dfrac{9x-23}{\left(x-2\right)\left(x-3\right)}=\dfrac{1}{x}\)
=>9x^2-23x=x^2-5x+6
=>8x^2-18x-6=0
=>\(x=\dfrac{9\pm\sqrt{129}}{8}\)
b: =>\(\dfrac{12x+1}{11x-4}=\dfrac{20x+17-20x+8}{18}=\dfrac{25}{18}\)
=>216x+18=275x-100
=>-59x=-118
=>x=2
ĐKXĐ x\(\ne\) \(\dfrac{4}{11}\)
\(\Rightarrow\left(12x+1\right)18+\left(10x-4\right)\left(11x-4\right)2=\left(20x+17\right)\left(11x-4\right)\)
\(\Leftrightarrow216x+18+\left(110x^2-40x-44x+16\right)2=220x^2-80x+187x-68\)
\(\Leftrightarrow216x+18+220x^2-168x+32=220x^2+107x-68\Leftrightarrow220x^2-48x+50=220x^2+107x-68\Leftrightarrow220x^2+107x+48x-220x^2=50+68\Leftrightarrow155x=138\Leftrightarrow x=\dfrac{138}{155}\left(TM\right)\)Vậy...
f: =>\(\dfrac{14}{3\left(x-4\right)}-\dfrac{x+2}{x-4}=\dfrac{-3}{2\left(x-4\right)}-\dfrac{5}{6}\)
=>28-6(x+2)=-9-5(x-4)
=>28-6x-12=-9-5x+20
=>-6x+16=-5x+11
=>-x=-5
=>x=5
d: =>\(\dfrac{12x+1}{11x-4}=\dfrac{20x+17-20x+8}{18}=\dfrac{25}{18}\)
=>25(11x-4)=18(12x+1)
=>275x-100=216x+18
=>59x=118
=>x=2
f: =>\(\dfrac{14}{3\left(x-4\right)}-\dfrac{x+2}{x-4}=\dfrac{-3}{2\left(x-4\right)}-\dfrac{5}{6}\)
=>28-6(x+2)=-9-5(x-4)
=>28-6x-12=-9-5x+20
=>-6x+16=-5x+11
=>-x=-5
=>x=5
bạn tách một câu vài câu hỏi chứ đừng gộp như thế này ko ai trả lời đâu
a: =>\(4x-5=2x-2+x=3x-2\)
=>x=3
b: \(\Leftrightarrow7x-35=3x+6\)
=>4x=41
=>x=41/4
c: =>(2x+5)(x+5)-2x^2=0
=>2x^2+10x+5x+25-2x^2=0
=>15x=-25
=>x=-5/3
e: \(\Leftrightarrow\dfrac{11}{x}=\dfrac{9x-36+2x+2}{\left(x+1\right)\left(x-4\right)}\)
=>11(x^2-3x-4)=x(11x-34)
=>11x^2-33x-44=11x^2-34x
=>x=44
a: =>10x-4=15-9x
=>19x=19
hay x=1
b: \(\Leftrightarrow3\left(10x+3\right)=36+4\left(8x+6\right)\)
=>30x+9=36+32x+24
=>30x-32x=60-9
=>-2x=51
hay x=-51/2
c: \(\Leftrightarrow2x+\dfrac{6}{5}=5-\dfrac{13}{5}-x\)
=>3x=6/5
hay x=2/5
d: \(\Leftrightarrow\dfrac{7x}{8}-\dfrac{5\left(x-9\right)}{1}=\dfrac{20x+1.5}{6}\)
\(\Leftrightarrow21x-120\left(x-9\right)=4\left(20x+1.5\right)\)
=>21x-120x+1080=80x+60
=>-179x=-1020
hay x=1020/179
e: \(\Leftrightarrow5\left(7x-1\right)+60x=6\left(16-x\right)\)
=>35x-5+60x=96-6x
=>95x+6x=96+5
=>x=1
f: \(\Leftrightarrow6\left(x+4\right)+30\left(-x+4\right)=10x-15\left(x-2\right)\)
=>6x+24-30x+120=10x-15x+30
=>-24x+96=-5x+30
=>-19x=-66
hay x=66/19
$ĐKXĐ:x \neq -4;-5;-6;-7$
$pt⇔\dfrac{1}{x^2+4x+5x+20}+\dfrac{1}{x^2+5x+6x+30}+\dfrac{1}{x^2+6x+7x+42}=\dfrac{1}{18}$
$⇔\dfrac{1}{(x+4)(x+5)}+\dfrac{1}{(x+5)(x+6)}+\dfrac{1}{(x+6)(x+7)}=\dfrac{1}{18}$
$⇔\dfrac{1}{x+4}-\dfrac{1}{x+5}+\dfrac{1}{x+5}-\dfrac{1}{x+6}+\dfrac{1}{x+6}-\dfrac{1}{x+7}=\dfrac{1}{18}$
$⇔\dfrac{1}{x+4}-\dfrac{1}{x+7}=\dfrac{1}{18}$
$⇔\dfrac{3}{(x+4)(x+7)}=\dfrac{1}{18}$
$⇔x^2+11x+28=54$
$⇔x^2+11x-26=0$
$⇔x^2-2x+13x-26=0$
$⇔(x-2)(x+13)=0$
$⇔$ \(\left[{}\begin{matrix}x=2\\x=-13\end{matrix}\right.\)(t/m)
Vậy phương trình đã cho có tập nghiệm $S=(2;-13)$
\(\frac{12x+1}{11x-4}+\frac{10x-4}{9}=\frac{20x+17}{18}\left(ĐKXĐ:x\ne\frac{4}{11}\right).\)
\(\Leftrightarrow\frac{18.\left(12x+1\right)}{18.\left(11x-4\right)}+\frac{2.\left(11x-4\right).\left(10x-4\right)}{18.\left(11x-4\right)}=\frac{\left(11x-4\right).\left(20x+17\right)}{18.\left(11x-4\right)}\)
\(\Rightarrow18.\left(12x+1\right)+2.\left(11x-4\right).\left(10x-4\right)=\left(11x-4\right).\left(20x+17\right)\)
\(\Leftrightarrow216x+18+\left(22x-8\right).\left(10x-4\right)=220x^2+187x-80x-68\)
\(\Leftrightarrow216x+18+220x^2-88x-80x+32=220x^2+107x-68\)
\(\Leftrightarrow48x+50+220x^2=220x^2+107x-68\)
\(\Leftrightarrow48x+50+220x^2-220x^2-107x+68=0\)
\(\Leftrightarrow118-59x=0\)
\(\Leftrightarrow59x=118-0\)
\(\Leftrightarrow59x=118\)
\(\Leftrightarrow x=118:59\)
\(\Leftrightarrow x=2\left(TM\right).\)
Vậy phương trình có tập hợp nghiệm là: \(S=\left\{2\right\}.\)
Chúc bạn học tốt!