Giaỉ ptr
(2x-1)(5x-3)-(2x-1)^2=0
Giaỉ ptr : 3-2x=3(x+1)-x-2
3 - 2x = 3(x + 1) - x - 2
⇔ 3 - 2x = 3x + 3 - x - 2
⇔ 4x = 2
⇔ x = 1/2
Giaỉ hệ phương trình sau bằng phương pháp thế
a)\(\dfrac{1}{x}+\dfrac{1}{y}=\dfrac{1}{2};\dfrac{3}{x}-\dfrac{4}{y}=-1\)
b)\(\dfrac{3}{2x-y}-\dfrac{6}{x+y}=-1;\dfrac{1}{2x-y}-\dfrac{1}{x+y}=0\)
c)\(\dfrac{5x}{x+1}+\dfrac{y}{y-3}=27;\dfrac{2x}{x+1}-\dfrac{3y}{y-3}=4\)
d)\(\dfrac{7}{x+2}+\dfrac{3}{y}=2;\dfrac{4}{x+2}-\dfrac{1}{y}=\dfrac{5}{2}\)
e)\(\dfrac{2x}{x+4}+\dfrac{2y}{2y-3}=27;\dfrac{2x}{x+4}-\dfrac{6y}{2y-3}=4\)
Bạn nào biết thì giải giúp mình với ạ,mình xin cảm ơn ạ!!!
2x^3-5x^2+7x-4=0 ..
Gấp lắm ạ....Giaỉ dùm với nhang....Thanks nhìu..!!
Giaỉ bất phương trình sau:
a,2x-3≥7
b,-5x-1≤x+5
a: =>2x>=10
hay x>=5
b: =>-6x<=6
hay x>=-1
a. \(\Leftrightarrow2x\ge10\Leftrightarrow x\ge5\)
b.\(-5x-1\le x+5\Leftrightarrow-6\le6x\Leftrightarrow x\ge-1\)
1 : giải ptr : \(\frac{x+2}{x-2}-\frac{2x-1}{x^2+3x+2}=\frac{5}{2}\)
2 giải ptr :
a, \(\left(x-2\right)\left(x^2+5x-7\right)=0\)
b, \(x^3+3x^2-4x-12=0\)
c, ( x+1 ) ( x+2 ) (x+4 ) ( x+5 )=40
\(\left(x+1\right)\left(x+2\right)\left(x+4\right)\left(x+5\right)=40\)
\(\Leftrightarrow\left(x+1\right)\left(x+5\right)\left(x+2\right)\left(x+4\right)=40\)
\(\Leftrightarrow\left(x^2+6x+5\right)\left(x^2+6x+8\right)=40\)
\(\Leftrightarrow\left(x^2+6x+5\right)\left(x^2+6x+5+3\right)=40\)
\(\Leftrightarrow p\left(p+3\right)=40\) (khi đặt \(\left(x^2+6x+5\right)=p\)
\(\Leftrightarrow p^2+3p=40\)
\(\Leftrightarrow p^2\cdot2\cdot p\cdot\frac{3}{2}+\left(\frac{3}{2}\right)^2=\frac{169}{4}\)
\(\Leftrightarrow\left(p+\frac{3}{2}\right)^2-\left(\frac{13}{2}\right)^2=0\)
\(\Leftrightarrow\left(p+\frac{3}{2}-\frac{13}{2}\right)\left(p+\frac{3}{2}+\frac{13}{2}\right)=0\)
\(\Leftrightarrow\left(p-5\right)\left(p+8\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}p=5\\p=-8\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x^2+6x+5=5\\x^2+6x+5=-8\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x^2+6x=0\\x^2+2\cdot x\cdot3+9-9+5=-8\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x\left(x+6\right)=0\\\left(x+3\right)^2=-4\left(\text{vôlí}\right)\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=0\\x=-6\end{cases}}\)
\(\left(x-2\right)\left(x^2+5x-7\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x=2\\x^2+5x-7=0\end{cases}}\)
Ta có: \(\Delta=25-4\cdot\left(-7\right)=25+28=53\)
\(\Rightarrow\Delta>0\)
\(\Rightarrow\text{pt có 2 nghiệm pb}\)
\(\Rightarrow\hept{\begin{cases}x_1=\frac{-5-\sqrt{53}}{2}\\x_2=\frac{-5+\sqrt{53}}{2}\end{cases}}\)
\(\text{Vậy pt trên có nghiệm là x=2; x=}\frac{-5\pm\sqrt{53}}{2}\)
\(x^3+3x^2-4x-12=0\)
\(\Leftrightarrow x^2\left(x+3\right)-4\left(x+3\right)=0\)
\(\Leftrightarrow\left(x^2-4\right)\left(x+3\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x^2=4\\x=-3\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=2\\x=-3\end{cases}}\)
\(\text{Vậy pt có nghiệm là x=2;x=-3}\)
giai cac ptr sau
a,\(x^4-5x^2+4=0\)
b,\(2x^4-3x^2-2=0\)
c,\(x-5\sqrt{x}-6=0\)
a: =>(x^2-1)(x^2-4)=0
=>(x-1)(x+1)(x-2)(x+2)=0
=>\(x\in\left\{1;-1;2;-2\right\}\)
b: =>2x^4-4x^2+x^2-2=0
=>(x^2-2)(2x^2+1)=0
=>x^2-2=0
=>\(x=\pm\sqrt{2}\)
c: =>(căn x-6)(căn x+1)=0
=>căn x-6=0
=>x=36
giaỉ phương trình: x^2 -2x+3 -3/x-1/ = 0
Giaỉ phương trình sau:
\(x^4+2x^3-2x^2+2x-3=0\)
Giaỉ phương trình nghiệm nguyên \(2x^2y^4+2y^4+y^2+5x+2y+2x^2+1=5xy^4\)