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\(x^2-5x+6=\left(x-3\right)\left(x-2\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x-3=0\\x-2=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=3\\x=2\end{cases}}}\)
1, <=>x^2-x-2 = x^2-4
<=>x^2-4-x^2+x+2 = 0
<=> x-2 = 0
<=> x=2
2, <=> (x-2).(x-3)=0
<=> x-2 = 0 hoặc x-3 = 0
<=> x=2 hoặc x=3
Ta có : x2(x - 1)2 + x(x2 - 1) = 2(x + 1)2
<=> x2(x2 - 2x + 1) + x3 - x - 2(x2 + 2x + 1) = 0
<=> x4 - 2x3 + x2 + x3 - x - 2x2 - 4x - 2 = 0
<=> x4 - x3 - x2 - 5x - 2 = 0
?
a,(x + 6)(3x +1) + x+6 = 0
(x+6)(3x +2)=0
x= -6
x= -2/3
b, x= -4 hoăc x =-8/5
a,(x+6)(3x+1)+x+6=0
=>(x+6)(3x+2)=0
=>x+6=0 hoặc 3x+2=0
=>x=-6 hoặc x=-2/3
b,(x+4)(5x+9)-x-4=0
=>(x+4)(5x+8)=0
=>x+4=0 hoặc 5x+8=0
=>x=-4 hoặc x=-8/5
BPT\(\Leftrightarrow\left(x-3\right)\left(x^2+3x+9\right)\left(x-1\right)\left(x^2+x+1\right)\left(3-x\right)\left(x+1\right)\ge0\)
\(\Leftrightarrow\left(x-3\right)\left(x-1\right)\left(3-x\right)\left(x+1\right)\ge0\) VÌ \(\left(\left(x^2+3x+9\right).\left(x^2+x+1\right)>0với\forall x\right)\)
\(\Leftrightarrow\left(x-3\right)^2.\left(1-x\right)\left(1+x\right)\ge0\)
\(\Leftrightarrow\left(1-x\right)\left(1+x\right)\ge0\left(vì\left(x-3\right)^2\ge0voi\forall x\right)\)
\(\Leftrightarrow-1\le x\le1\)
TA CÓ:
\(a,\left(4x-1\right)\left(x-3\right)=\left(x-3\right)\left(5x+2\right)\Leftrightarrow\left(4x-1\right)\left(x-3\right)-\left(x-3\right)\left(5x+2\right)=0\)
\(\left(x-3\right)\left(4x-1-5x-2\right)=0\Leftrightarrow\left(x-3\right)\left(-x-3\right)=0\orbr{\begin{cases}x=3\\x=-3\end{cases}}\)
\(b,\left(x+3\right)\left(x-5\right)+\left(x+3\right)\left(3x-4\right)=0\Leftrightarrow\left(x+3\right)\left(x-5+3x-4\right)=0\)
\(\left(x-3\right)\left(4x-9\right)=0\orbr{\begin{cases}x=3\\x=\frac{9}{4}\end{cases}}\)
\(c,\left(1-x\right)\left(5x+3\right)=\left(3x-7\right)\left(x-1\right)\Leftrightarrow\left(1-x\right)\left(5x+3\right)=\left(7-3x\right)\left(1-x\right)\)
\(\left(1-x\right)\left(5x+3-7+3x\right)=0\Leftrightarrow\left(1-x\right)\left(8x-4\right)=0\orbr{\begin{cases}x=1\\x=\frac{1}{2}\end{cases}}\)
\(a,\frac{x+1}{x-2}+\frac{x-1}{x+2}=\frac{2\left(x^2+2\right)}{x^2-4}\)\(\Leftrightarrow\frac{x^2+3x+2+x^2-3x+2}{x^2-4}=\frac{2\left(x^2+2\right)}{x^2-4}\)
\(\Leftrightarrow2\left(x^2+2\right)=2\left(x^2+2\right)\)(luôn đúng)
Vậy pt có vô số nghiệm
\(b,\Leftrightarrow\left(2x+3\right)\left(\frac{3x+8}{2-7x}+1\right)=\left(x-5\right)\left(\frac{3x+8}{2-7x}+1\right)\)
\(\Leftrightarrow\left(\frac{3x+8}{2-7x}+1\right)\left(2x+3-x+5\right)=0\)\(\Leftrightarrow\left(\frac{-4x+10}{2-7x}\right)\left(x+8\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}-4x+10=0\\x+8=0\end{cases}\Rightarrow}\orbr{\begin{cases}x=\frac{5}{2}\\x=-8\end{cases}}\)
Mấy câu rút gọn bạn quy đồng nha
\(\left(x+1\right)^2-\left(x-1\right)^2=6\left(x^2+x+1\right)\)
\(\Leftrightarrow\left(x+1+x-1\right)\left(x+1-x+1\right)=6\left(x^2+x+1\right)\)
\(\Leftrightarrow2x.2=6x^2+6x+6\)
\(\Leftrightarrow4x=6x^2+6x+6\)
\(\Leftrightarrow6x^2+2x+6=0\)
Ta có \(\Delta=2^2-4.6.6< 0\)
Vậy pt vô nghiệm
\(\left(x+1\right)^2-\left(x-1\right)^2=6\left(x^2+x+1\right)\)
\(\Leftrightarrow\left[\left(x+1\right)-\left(x-1\right)\right].\left[\left(x+1\right)+\left(x-1\right)\right]=6\left(x^2+x+1\right)\)
\(\Leftrightarrow\left(x+1-x+1\right)\left(x+1+x-1\right)=6x^2+6x+6\)
\(\Leftrightarrow2.2x=6x^2+6x+6\)\(\Leftrightarrow4x=6x^2+6x+6\)
\(\Leftrightarrow6x^2+2x+6=0\)\(\Leftrightarrow3x^2+x+3=0\)( vô nghiệm vì \(1^2< 4.3.3\)hay \(1< 36\))
Vậy tập nghiệm của phương trình là \(S=\varnothing\)