Giải phương trình:
a)\(\frac{3}{x^2+5x+4}\)+\(\frac{2}{x^2+10x+24}\)=\(\frac{4}{3}\)+\(\frac{9}{x^2+3x-18}\)
b) x2\(-\)y2+x\(-\)4y\(-\)10=0 (x; y \(\in\)N*)
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30 tháng 12 2018
a) \(x^3-2x^2-5x+6=0\)
\(x^3-x^2-x^2+x-6x+6=0\)
\(x^2\left(x-1\right)-x\left(x-1\right)-6\left(x-1\right)=0\)
\(\left(x-1\right)\left(x^2-x-6\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x-1=0\\x^2-x-6=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=1\\x^2-2x+3x-6=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=1\\\left(x+3\right)\left(x-2\right)=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=1\\x=\left\{2;-3\right\}\end{cases}}\)
30 tháng 12 2018
\(a,x^3-2x^2-5x+6=0\)
\(\Leftrightarrow\left(x^3-x^2\right)-\left(x^2-x\right)-\left(6x-6\right)=0\)
\(\Leftrightarrow x^2\left(x-1\right)-x\left(x-1\right)-6\left(x-1\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(x^2-x-6\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left[\left(x^2-3x\right)+\left(2x-6\right)\right]=0\)
\(\Leftrightarrow\left(x-1\right)\left[x\left(x-3\right)+2\left(x-3\right)\right]=0\)
\(\Leftrightarrow\left(x-1\right)\left(x+2\right)\left(x-3\right)=0\)
\(\Leftrightarrow x-1=0\left(h\right)x+2=0\left(h\right)x-3=0\)
\(\Leftrightarrow x=1\left(h\right)x=-2\left(h\right)x=3\)
Vậy \(x\in\left\{-2;1;3\right\}\)
P/S: (h) là hoặc nhé
28 tháng 4 2020
a) Ta có: \(\frac{3x-2}{6}-\frac{4-3x}{18}=\frac{4-x}{9}\)
\(\Leftrightarrow\frac{3\left(3x-2\right)}{18}-\frac{4-3x}{18}-\frac{2\left(4-x\right)}{18}=0\)
\(\Leftrightarrow9x-6-4+3x-\left(8-2x\right)=0\)
\(\Leftrightarrow12x-10-8+2x=0\)
\(\Leftrightarrow10x-18=0\)
\(\Leftrightarrow10x=18\)
hay \(x=\frac{9}{5}\)
Vậy: \(x=\frac{9}{5}\)
b) Ta có: \(\frac{2+3x}{6}-x+2=\frac{x-7}{9}\)
\(\Leftrightarrow\frac{3\left(2+3x\right)}{18}-\frac{18x}{18}+\frac{36}{18}-\frac{2\left(x-7\right)}{18}=0\)
\(\Leftrightarrow6+9x-18x+36-\left(2x-14\right)=0\)
\(\Leftrightarrow42-9x-2x+14=0\)
\(\Leftrightarrow56-11x=0\)
\(\Leftrightarrow11x=56\)
hay \(x=\frac{56}{11}\)
Vậy: \(x=\frac{56}{11}\)
c) ĐKXĐ: x∉{3;-3}
Ta có: \(\frac{6-x}{x^2-9}+\frac{2}{x+3}=\frac{-5}{x-3}\)
\(\Leftrightarrow\frac{6-x}{\left(x-3\right)\left(x+3\right)}+\frac{2\left(x-3\right)}{\left(x+3\right)\left(x-3\right)}=\frac{-5\left(x+3\right)}{\left(x-3\right)\left(x+3\right)}\)
\(\Leftrightarrow6-x+2x-6=-5x-15\)
\(\Leftrightarrow x+5x+15=0\)
\(\Leftrightarrow6x=-15\)
hay \(x=\frac{-5}{2}\)(tm)
Vậy: \(x=\frac{-5}{2}\)
d) Ta có: \(\left(5x+2\right)\left(x^2-7\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}5x+2=0\\x^2-7=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}5x=-2\\x^2=7\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\frac{-2}{5}\\x=\pm\sqrt{7}\end{matrix}\right.\)
Vậy: \(x\in\left\{\frac{-2}{5};\sqrt{7};-\sqrt{7}\right\}\)
e) ĐKXĐ: x∉{4;-4}
Ta có: \(\frac{3}{x-4}+\frac{5x-2}{x^2-16}=\frac{4}{x+4}\)
\(\Leftrightarrow\frac{3\left(x+4\right)}{\left(x-4\right)\left(x+4\right)}+\frac{5x-2}{\left(x-4\right)\left(x+4\right)}-\frac{4\left(x-4\right)}{\left(x-4\right)\left(x+4\right)}=0\)
\(\Leftrightarrow3x+12+5x-2-\left(4x-16\right)=0\)
\(\Leftrightarrow8x+10-4x+16=0\)
\(\Leftrightarrow4x+26=0\)
\(\Leftrightarrow4x=-26\)
hay \(x=\frac{-13}{2}\)(tm)
Vậy: \(x=\frac{-13}{2}\)
11 tháng 5 2018
\(\text{a) }\dfrac{3}{x^2+5x+4}+\dfrac{2}{x^2+10x+24}=\dfrac{4}{3}+\dfrac{9}{x^2+3x-18}\\ ĐKXĐ:x\ne-1;x\ne-3;x\ne-4;x\ne-6\\ \Rightarrow\dfrac{3}{x^2+4x+x+4}+\dfrac{2}{x^2+6x+4x+24}=\dfrac{4}{3}+\dfrac{9}{x^2+6x-3x-18}\\ \Rightarrow\dfrac{3}{x\left(x+4\right)+\left(x+4\right)}+\dfrac{2}{x\left(x+6\right)+4\left(x+6\right)}=\dfrac{4}{3}+\dfrac{9}{x\left(x+6\right)-3\left(x+6\right)}\\ \Rightarrow\dfrac{3}{\left(x+1\right)\left(x+4\right)}+\dfrac{2}{\left(x+4\right)\left(x+6\right)}=\dfrac{4}{3}+\dfrac{9}{\left(x-3\right)\left(x+6\right)}\)\(\Rightarrow\dfrac{1}{x+1}-\dfrac{1}{x+4}+\dfrac{1}{x+4}-\dfrac{1}{x+6}=\dfrac{4}{3}+\dfrac{1}{x-3}-\dfrac{1}{x+6}\\ \Rightarrow\dfrac{1}{x+1}-\dfrac{1}{x+6}-\dfrac{1}{x-3}+\dfrac{1}{x+6}=\dfrac{4}{3}\\ \Rightarrow\dfrac{1}{x+1}-\dfrac{1}{x-3}=\dfrac{4}{3}\\ \Rightarrow\dfrac{3\left(x-3\right)}{3\left(x+1\right)\left(x-3\right)}-\dfrac{3\left(x+1\right)}{3\left(x+1\right)\left(x-3\right)}=\dfrac{4\left(x+1\right)\left(x-3\right)}{3\left(x+1\right)\left(x-3\right)}\\ \Rightarrow3x-9-3x-3=4\left(x^2-2x-3\right)\\ \Leftrightarrow4x^2-8x-12=-12\\ \Leftrightarrow4x^2-8x=0\\ \Leftrightarrow4x\left(x-2\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}4x=0\\x-2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=2\end{matrix}\right.\)Vậy phương trình có tập nghiệm \(S=\left\{0;2\right\}\)
LV
1
26 tháng 2 2022
a: =>5x-5+17x=1-12x-4
=>22x-5=-12x-3
=>34x=2
hay x=1/17
b: =>\(\left(x-3\right)^2-4x\left(x-3\right)=0\)
=>(x-3)(-3x-3)=0
=>x=3 hoặc x=-1
c: =>(x-4)(x-6)=0
=>x=4 hoặc x=6
HH
3 tháng 7 2020
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
24 tháng 3 2020
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