(x^2+8x+16)(x^2+16x+48) -165x^2=0
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2: \(x^2-2xy+y^2-2x+2y\)
\(=\left(x-y\right)^2-2\left(x-y\right)\)
=(x-y)(x-y-2)
3: \(3x^2-2x-5\)
\(=3x^2-5x+3x-5\)
=x(3x-5)+(3x-5)
=(3x-5)(x+1)
4: \(16-x^2+4xy-4y^2\)
\(=16-\left(x^2-4xy+4y^2\right)\)
\(=4^2-\left(x-2y\right)^2\)
=(4-x+2y)(4+x-2y)
5: \(x^2-2x+1-y^2\)
\(=\left(x-1\right)^2-y^2\)
=(x-1-y)(x-1+y)
6: \(x^2+8x+15\)
\(=x^2+3x+5x+15\)
=x(x+3)+5(x+3)
=(x+3)(x+5)
7: \(\left(x^2+6x+8\right)\left(x^2+14x+48\right)-9\)
=(x+2)(x+4)(x+6)(x+8)-9
\(=\left(x^2+10x+16\right)\left(x^2+10x+24\right)-9\)
\(=\left(x^2+10x\right)^2+40\left(x^2+10x\right)+384-9\)
\(=\left(x^2+10x\right)^2+15\left(x^2+10x\right)+25\left(x^2+10x\right)+375\)
\(=\left(x^2+10x+25\right)\left(x^2+10x+15\right)=\left(x+5\right)^2\cdot\left(x^2+10x+15\right)\)
8: \(\left(x^2-8x+15\right)\left(x^2-16x+60\right)-24x^2\)
\(=\left(x-3\right)\left(x-5\right)\left(x-6\right)\left(x-10\right)-24x^2\)
\(=\left(x^2-13x+30\right)\left(x^2-11x+30\right)-24x^2\)
\(=\left(x^2+30\right)^2-24x\left(x^2+30\right)+143x^2-24x^2\)
\(=\left(x^2+30\right)^2-24x\left(x^2+30\right)+119x^2\)
\(=\left(x^2-7x+30\right)\left(x^2-17x+30\right)\)
\(=\left(x^2-7x+30\right)\left(x-2\right)\left(x-15\right)\)
mk sửa đề 1 chút
\(x^6-x^5+3x^4-16x^2+16x-48=0\)
\(\Leftrightarrow\left(x^6-16x^2\right)-\left(x^5-16x\right)+\left(3x^4-48\right)=0\)
\(\Leftrightarrow x^2\left(x^4-16\right)-x\left(x^4-16\right)+3\left(x^4-16\right)=0\)
\(\Leftrightarrow\left(x^4-16\right)\left(x^2-x+3\right)=0\)
\(\Leftrightarrow\left(x^2-4\right)\left(x^2+4\right)\left(x^2-x+3\right)=0\)
\(\Leftrightarrow\left(x-2\right)\left(x+2\right)\left(x^2+4\right)\left(x^2-x+3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-2=0\\x+2=0\\x^2+4>0\\x^2-x+3=0\left(vonghiem\right)\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2\\x=-2\end{matrix}\right.\)
Vậy.............
a, 4x2 - 49 = 0
⇔⇔ (2x)2 - 72 = 0
⇔⇔ (2x - 7)(2x + 7) = 0
⇔{2x−7=02x+7=0⇔⎧⎪ ⎪⎨⎪ ⎪⎩x=72x=−72⇔{2x−7=02x+7=0⇔{x=72x=−72
b, x2 + 36 = 12x
⇔⇔ x2 + 36 - 12x = 0
⇔⇔ x2 - 2.x.6 + 62 = 0
⇔⇔ (x - 6)2 = 0
⇔⇔ x = 6
e, (x - 2)2 - 16 = 0
⇔⇔ (x - 2)2 - 42 = 0
⇔⇔ (x - 2 - 4)(x - 2 + 4) = 0
⇔⇔ (x - 6)(x + 2) = 0
⇔{x−6=0x+2=0⇔{x=6x=−2⇔{x−6=0x+2=0⇔{x=6x=−2
f, x2 - 5x -14 = 0
⇔⇔ x2 + 2x - 7x -14 = 0
⇔⇔ x(x + 2) - 7(x + 2) = 0
⇔⇔ (x + 2)(x - 7) = 0
⇔{x+2=0x−7=0⇔{x=−2x=7
`a) x^3 - 9x^2 + 14x = 0`
\(\Rightarrow\) `x^3 - 7x^2 - 2x^2 + 14x = 0`
\(\Rightarrow\) `(x^3 - 2x^2) - (7x^2 - 14x) =0`
\(\Rightarrow\) `x^2.(x - 2) - 7x.(x - 2) =0`
\(\Rightarrow\) `(x^2 - 7x)(x-2)=0`
\(\Rightarrow\) `x.(x-7)(x-2)=0`
\(\Rightarrow\left[\begin{array}{l}x=0\\ x-7=0\\ x-2=0\end{array}\right.\) \(\Rightarrow\left[\begin{array}{l}x=0\\ x=0+7\\ x=0+2\end{array}\right.\) \(\Rightarrow\left[\begin{array}{l}x=0\\ x=7\\ x=2\end{array}\right.\)
Vậy \(x\in\left\lbrace0;7;2\right\rbrace\)
`3.x^3 - 5x^2 + 8x - 4 = 0`
\(\Rightarrow\) `x^3 - x^2 - 4x^2 + 4x + 4x - 4 =0`
\(\Rightarrow\) `x^2 . (x-1) - 4x(x-1) + 4.(x-1) =0`
\(\Rightarrow\) `(x^2 - 4x + 4)(x-1)=0`
\(\Rightarrow\) `(x-2)^2(x-1)=0`
\(\Rightarrow\left[\begin{array}{l}x-2=0\\ x-1=0\end{array}\right.\) \(\Rightarrow\left[\begin{array}{l}x=2\\ x=1\end{array}\right.\)
Vậy \(x\in\left\lbrace2;1\right\rbrace\)
1: =(16x^2-8x+1)-y^2
=(4x-1)^2-y^2
=(4x-1-y)(4x-1+y)
2: =(x^2-2xy+y^2)-z^2
=(x-y)^2-z^2
=(x-y-z)(x-y+z)
3: =(x^2+4xy+4y^2)-16
=(x+2y)^2-4^2
=(x+2y-4)(x+2y+4)
4: =(x^2-4xy+4y^2)-16
=(x-2y)^2-4^2
=(x-2y-4)(x-2y+4)