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1) ĐKXĐ: \(x\notin\left\{1;-1\right\}\)
Ta có: \(\dfrac{x+1}{x-1}-\dfrac{x-1}{x+1}=\dfrac{4}{x^2-1}\)
\(\Leftrightarrow\dfrac{\left(x+1\right)^2}{\left(x-1\right)\left(x+1\right)}-\dfrac{\left(x-1\right)^2}{\left(x-1\right)\left(x+1\right)}=\dfrac{4}{\left(x-1\right)\left(x+1\right)}\)
Suy ra: \(x^2+2x+1-\left(x^2-2x+1\right)=4\)
\(\Leftrightarrow x^2+2x+1-x^2+2x-1=4\)
\(\Leftrightarrow4x=4\)
hay x=1(loại)
Vậy: \(S=\varnothing\)
2) ĐKXĐ: \(x\notin\left\{2;-2\right\}\)
Ta có: \(\dfrac{x+2}{x-2}+\dfrac{x}{x+2}=2\)
\(\Leftrightarrow\dfrac{\left(x+2\right)^2}{\left(x-2\right)\left(x+2\right)}+\dfrac{x\left(x-2\right)}{\left(x-2\right)\left(x+2\right)}=\dfrac{2\left(x^2-4\right)}{\left(x-2\right)\left(x+2\right)}\)
Suy ra: \(x^2+4x+4+x^2-2x=2x^2-8\)
\(\Leftrightarrow2x^2+2x+4-2x^2-8=0\)
\(\Leftrightarrow2x-4=0\)
\(\Leftrightarrow2x=4\)
hay x=2(loại)
Vậy: \(S=\varnothing\)
a: \(\dfrac{x+5}{x-1}+\dfrac{8}{x^2-4x+3}=\dfrac{x+1}{x-3}\)
=>(x+5)(x-3)+8=x^2-1
=>x^2+2x-15+8=x^2-1
=>2x-7=-1
=>x=3(loại)
b: \(\dfrac{x-4}{x-1}-\dfrac{x^2+3}{1-x^2}+\dfrac{5}{x+1}=0\)
=>(x-4)(x+1)+x^2+3+5(x-1)=0
=>x^2-3x-4+x^2+3+5x-5=0
=>2x^2+2x-6=0
=>x^2+x-3=0
=>\(x=\dfrac{-1\pm\sqrt{13}}{2}\)
e: =>x^2-2x+1+2x+2=5x+5
=>x^2+3=5x+5
=>x^2-5x-2=0
=>\(x=\dfrac{5\pm\sqrt{33}}{2}\)
g: (x-3)(x+4)*x=0
=>x=0 hoặc x-3=0 hoặc x+4=0
=>x=0;x=3;x=-4
1:
\(\Leftrightarrow\left(x^2+5x+6\right)\left(x^2+5x+4\right)=24\)
\(\Leftrightarrow\left(x^2+5x\right)^2+10\left(x^2+5x\right)=0\)
\(\Leftrightarrow x^2+5x=0\)
=>x=0 hoặc x=-5
3: \(\Leftrightarrow\left(x^2+x+6\right)\left(x^2+x-2\right)=0\)
=>(x+2)(x-1)=0
=>x=-2 hoặc x=1
1: \(\frac{3x-2}{3}-2=\frac{4x+1}{4}\)
=>\(\frac{3x-2-6}{3}=\frac{4x+1}{4}\)
=>\(\frac{3x-8}{3}=\frac{4x+1}{4}\)
=>3(4x+1)=4(3x-8)
=>12x+3=12x-32
=>3=-32(vô lý)
=>Phương trình vô nghiệm
2: \(\frac{x-3}{4}+\frac{2x-1}{3}=\frac{2-x}{6}\)
=>\(\frac{3\left(x-3\right)+4\left(2x-1\right)}{12}=\frac{2\left(2-x\right)}{12}\)
=>3(x-3)+4(2x-1)=2(2-x)
=>3x-9+8x-4=4-2x
=>11x-13=4-2x
=>13x=17
=>\(x=\frac{17}{13}\)
3: \(\frac12\left(x+1\right)+\frac14\left(x+3\right)=3-\frac13\left(x+2\right)\)
=>\(\frac12x+\frac12+\frac14x+\frac34+\frac13x+\frac23=3\)
=>\(x\left(\frac12+\frac14+\frac13\right)+\frac{6}{12}+\frac{9}{12}+\frac{8}{12}=3\)
=>\(x\left(\frac{6}{12}+\frac{3}{12}+\frac{4}{12}\right)=3-\frac{23}{12}=\frac{36}{12}-\frac{23}{12}=\frac{13}{12}\)
=>\(x\cdot\frac{13}{12}=\frac{13}{12}\)
=>x=1
4: \(\frac{x+4}{5}-x+4=\frac{x}{3}-\frac{x-2}{2}\)
=>\(\frac{x+4}{5}+\frac{5\left(-x+4\right)}{5}=\frac{2x-3\left(x-2\right)}{6}\)
=>\(\frac{x+4-5x+20}{5}=\frac{2x-3x+6}{6}\)
=>\(\frac{-4x+24}{5}=\frac{-x+6}{6}\)
=>6(-4x+24)=5(-x+6)
=>-24x+144=-5x+30
=>-19x=-114
=>x=6
5: \(\frac{4-5x}{6}=\frac{2\left(-x+1\right)}{2}\)
=>\(\frac{4-5x}{6}=-x+1\)
=>6(-x+1)=-5x+4
=>-6x+6=-5x+4
=>-6x+5x=4-6
=>-x=-2
=>x=2
6: \(-\left(\frac{x-3}{2}-2\right)=\frac{5\left(x+2\right)}{4}\)
=>\(-\frac{x-3-4}{2}=\frac{5\left(x+2\right)}{4}\)
=>\(\frac{-2\left(x-7\right)}{4}=\frac{5\left(x+2\right)}{4}\)
=>5(x+2)=-2(x-7)
=>5x+10=-2x+14
=>7x=4
=>x=4/7
7: \(\frac{2\left(2x+1\right)}{5}-\frac{6+x}{3}=\frac{5-4x}{15}\)
=>\(\frac{6\left(2x+1\right)-5\left(x+6\right)}{15}=\frac{5-4x}{15}\)
=>6(2x+1)-5(x+6)=-4x+5
=>12x+6-5x-30=-4x+5
=>7x-24=-4x+5
=>7x+4x=5+24
=>11x=29
=>\(x=\frac{29}{11}\)
8: \(\frac{7-3x}{2}-\frac{5+x}{5}=1\)
=>\(\frac{5\left(7-3x\right)-2\left(x+5\right)}{10}=1\)
=>5(7-3x)-2(x+5)=10
=>35-15x-2x-10=10
=>-17x+25=10
=>-17x=-15
=>x=15/17
a, \(-\left(x+3\right)\left(x-4\right)+\left(x+1\right)\left(x-1\right)=10\)
\(\Rightarrow-\left(x^2-4x+3x-12\right)+x^2-1=10\)
\(\Rightarrow-x^2+x+12+x^2-1=10\)
\(\Rightarrow x=10+1-12\Rightarrow x=-1\)
b, \(\left(2x-1\right)\left(x-2\right)-\left(x+3\right)\left(2x-7\right)=3\)
\(\Rightarrow2x^2-4x-x+2-\left(2x^2-7x+6x-21\right)=3\)
\(\Rightarrow2x^2-5x+2-2x^2+x+21=3\)
\(\Rightarrow-4x=3-21-2\Rightarrow-4x=-20\)
\(\Rightarrow x=5\)
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\(\frac{1-x}{1+x}+3=\frac{2x+3}{x+1}\left(ĐKXĐ:x\ne-1\right)\)
\(\Leftrightarrow\frac{1-x}{x+1}+\frac{3\left(x+1\right)}{x+1}=\frac{2x+3}{x+1}\)
\(\Leftrightarrow\frac{1-x+3\left(x+1\right)}{x+1}=\frac{2x+3}{x+1}\)
\(\Rightarrow1-x+3\left(x+1\right)=2x+3\)
\(\Leftrightarrow1-x+3x+3=2x+3\)
\(\Leftrightarrow2x+4=2x+3\)
\(\Leftrightarrow0x=-1\)(vô nghiệm)
Vậy phương trình vô nghiệm.
\(\frac{\left(x+2\right)^2}{2x-3}-1=\frac{x^2-10}{2x-3}\left(ĐKXĐ:x\ne\frac{3}{2}\right)\)
\(\Leftrightarrow\frac{x^2+4x+4}{2x-3}-\frac{2x-3}{2x-3}=\frac{x^2-10}{2x-3}\)
\(\Leftrightarrow\frac{x^2+4x+4-2x+3}{2x-3}=\frac{x^2-10}{2x-3}\)
\(\Rightarrow x^2+4x+4-2x+3=x^2-10\)
\(\Leftrightarrow2x+7=-10\)
\(\Leftrightarrow2x=-17\)
\(\Leftrightarrow x=\frac{-17}{2}\)(thỏa mãn ĐKXĐ)
Vậy phương trình có nghiệm duy nhất : \(x=\frac{-17}{2}\)
Bạn cần viết đề bài bằng công thức toán để được hỗ trợ tốt hơn.
\(1)\left(x+1\right)^3-\left(x-1\right)^3-6\left(x-1\right)\left(x-1\right)\\ =x^3+3x^2+3x+1-x^3+3x^2-3x+1-6\cdot\left(x-1\right)^2\\ =6x^2+2-6\cdot\left(x^2-2x+1\right)\\ =6x^2+2-6x^2+12x-6\\ =12x-4\)
\(2)x\left(x-1\right)\left(x+1\right)-\left(x+1\right)\left(x^2-x+1\right)\\ =x\left(x^2-1\right)-\left(x^3+1\right)\\ =x^3-x-x^3-1\\=-x-1\)
\(3)\left(x-1\right)^3-\left(x+2\right)\left(x^2-2x+4\right)+3\left(x-4\right)\left(x+4\right)\\ =x^3-3x^2+3x-1-(x^3+8)+3\cdot\left(x^2-16\right)\\ =x^3-3x^2+3x-1-x^3-8+3x^2-48\\ =3x-55\)
\(\frac{x^2+1}{x+x^3}-\frac{1}{x^2-x}+\frac{x^4-x^3+x-1}{x-x^3}\)
\(=\frac{x^2+1}{x\left(x^2+1\right)}-\frac{1}{x\left(x-1\right)}-\frac{x^3\left(x-1\right)+\left(x-1\right)}{x^3-x}\)
\(=\frac{1}{x}-\frac{1}{x\left(x-1\right)}-\frac{\left(x-1\right)\left(x^3+1\right)}{x\left(x^2-1\right)}\)
\(=\frac{1}{x}-\frac{1}{x\left(x-1\right)}-\frac{\left(x-1\right)\left(x+1\right)\left(x^2-x+1\right)}{x\left(x-1\right)\left(x+1\right)}=\frac{1}{x}-\frac{1}{x\left(x-1\right)}-\frac{x^2-x+1}{x}\)
\(=\frac{1-x^2+x-1}{x}-\frac{1}{x\left(x-1\right)}=\frac{-x^2+x}{x}-\frac{1}{x\left(x-1\right)}\)
\(=\frac{x\left(-x+1\right)}{x}-\frac{1}{x\left(x-1\right)}=-x+1-\frac{1}{x\left(x-1\right)}=\frac{\left(-x+1\right)\cdot x\left(x-1\right)-1}{x\left(x-1\right)}\)
\(=\frac{-x\left(x-1\right)^2-1}{x\left(x-1\right)}=\frac{-x\left(x^2-2x+1\right)-1}{x\left(x-1\right)}=\frac{-x^3+2x^2-x-1}{x\left(x-1\right)}\)