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Bài 1 câu g bạn kia làm sai mình sửa lại nhá
\(3a^2-6ab+3b^2-12c^2\)
\(=3\left(a^2-2ab+b^2\right)-12c^2\)
\(=3\left(a-b\right)^2-12c^2\)
\(=3\left[\left(a-b\right)^2-4c^2\right]\)
\(=3\left(a-b-2c\right)\left(a-b+2c\right)\)
Để mình làm tiếp cho :))
Bài 2 :
Câu a : \(37,5.8,5-7,5.3,4-6,6.7,5+1,5.37,5\)
\(=\left(37,5.8,5+1,5.37,5\right)-\left(7,5.3,4+6,6.7,5\right)\)
\(=37,5\left(8,5+1,5\right)-7,5\left(3,4+6,6\right)\)
\(=37,5.10-7,5.10\)
\(=10.30=300\)
Câu b : \(35^2+40^2-25^2+80.35\)
\(=\left(35^2+80.35+40^2\right)-25^2\)
\(=\left(30+45\right)^2-25^2\)
\(=75^2-25^2\)
\(=\left(75+25\right)\left(75-25\right)\)
\(=100.50=5000\)
Bài 3 :
Câu a : \(x^3-\dfrac{1}{9}x=0\)
\(\Leftrightarrow x\left(x^2-\dfrac{1}{9}\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x^2-\dfrac{1}{9}=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x=\pm\dfrac{1}{3}\end{matrix}\right.\)
Câu b : \(2x-2y-x^2+2xy-y^2=0\)
\(\Leftrightarrow2\left(x-y\right)-\left(x-y\right)^2=0\)
\(\Leftrightarrow\left(x-y\right)\left(2-x+y\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-y=0\\2-x+y=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=y\\x+y=2\Rightarrow x=2-y\end{matrix}\right.\)
Câu c :
\(x\left(x-3\right)+x-3=0\)
\(\Leftrightarrow\left(x-3\right)\left(x+1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-3=0\\x+1=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=3\\x=-1\end{matrix}\right.\)
\(x^2\left(x-3\right)+27-9x=0\)
\(\Leftrightarrow x^2\left(x-3\right)-9\left(x-3\right)=0\)
\(\Leftrightarrow\left(x-3\right)\left(x^2-9\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-3=0\\x^2-9=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=3\\x=\pm3\end{matrix}\right.\)
Bài 4 :
Câu a :
\(x^2-4x+3\)
\(=x^2-x-3x+3\)
\(=\left(x^2-x\right)-\left(3x-3\right)\)
\(=x\left(x-1\right)-3\left(x-1\right)\)
\(=\left(x-1\right)\left(x-3\right)\)
Câu b :
\(x^2+x-6\)
\(=x^2-2x+3x-6\)
\(=x\left(x-2\right)+3\left(x-2\right)\)
\(=\left(x-2\right)\left(x+3\right)\)
Câu c :
\(x^2-5x+6\)
\(=x^2-2x-3x+6\)
\(=\left(x^2-2x\right)-\left(3x-6\right)\)
\(=x\left(x-2\right)-3\left(x-2\right)\)
\(=\left(x-2\right)\left(x-3\right)\)
Câu d :
\(x^4+4\)
\(=x^4+4x^2+4-4x^2\)
\(=\left(x^2+2\right)^2-\left(2x\right)^2\)
\(=\left(x^2+2-2x\right)\left(x^2+2+2x\right)\)
a: Sửa đề: x^3-x^2+5x-5
=x^2(x-1)+5(x-1)
=(x-1)(x^2+5)
b: x^3+4x^2+x-6
=x^3-x^2+5x^2-5x+6x-6
=(x-1)(x^2+5x+6)
=(x-1)(x+2)(x+3)
c: \(=\left(x+2\right)^3+y^3\)
\(=\left(x+2+y\right)\left(x^2+4x+4-xy-2y+y^2\right)\)
a)\(x^2+x-6\)
\(=x^2-2x+3x-6\)
\(=\left(x^2-2x\right)+\left(3x-6\right)\)
\(=x\left(x-2\right)+3\left(x-2\right)\)
\(=\left(x-2\right)\left(x+3\right)\)
a) x2 + x - 6
= x2 - 2x + 3x - 6
= (x2 - 2x) + (3x - 6)
= x(x - 2) + 3(x - 2)
= (x + 3)(x - 2)
b) x4 + 4
= x4 + 4x2 + 4 - 4x2
= (x4 + 4x2 + 4) - 4x2
= (x + 2)2 - 4x2
= (x + 2 - 2x)(x + 2 +2x)
\(\text{a) }x^4+x^2y^2+y^4=x^4+2x^2y^2-x^2y^2+y^4=\left(x^4+2x^2y^2+y^4\right)-\left(x^2y^2\right)=\left(x^2+y^2\right)^2-\left(xy\right)^2\)
\(=\left(x^2+y^2+xy\right)\left(x^2+y^2-xy\right)\)
\(\text{b) }x^3+3x-4=x^3+3x-1-3=\left(x^3-1\right)+\left(3x-3\right)=\left(x-1\right)\left(x^2+x+1\right)+3\left(x-1\right)\)
\(=\left(x-1\right)\left(x^2+x+1+3\right)=\left(x-1\right)\left(x^2+x+4\right)\)
\(\text{c) }x^2+9x+8=x^2+8x+x+8=\left(x^2+8x\right)+\left(x+8\right)=x\left(x+8\right)+\left(x+8\right)\)
\(=\left(x+8\right)\left(x+1\right)\)
\(\text{d) }x^2+x-42=x^2+7x-6x-42=\left(x^2+7x\right)-\left(6x+42\right)=x\left(x+7\right)-6\left(x+7\right)\)
\(=\left(x+7\right)\left(x-6\right)\)
\(\text{e) }y^2-13y+12=y^2-y-12y+12=\left(y^2-y\right)-\left(12y-12\right)=y\left(y-1\right)-12\left(y-1\right)\)
\(=\left(y-1\right)\left(y-12\right)\)
Mấy câu sau mk sẽ giải tiếp, bạn ráng chờ nha