3(x-2)(x^2+2x+4)-3x(x^2+1)=-30
biến đổi đa thức thành nhân tử (giúp mình nha)
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14 tháng 10 2016
a)\(2x^3+3x^2+2x+3=0\)
\(\Leftrightarrow2x^3+2x+3x^2+3=0\)
\(\Leftrightarrow2x\left(x^2+1\right)+3\left(x^2+1\right)=0\)
\(\Leftrightarrow\left(2x+3\right)\left(x^2+1\right)=0\)
\(\Leftrightarrow\left[\begin{array}{nghiempt}2x+3=0\\x^2+1=0\end{array}\right.\)
\(\Leftrightarrow\left[\begin{array}{nghiempt}2x=-3\\x^2+1>0\left(loai\right)\end{array}\right.\)
\(\Leftrightarrow x=-\frac{3}{2}\)
b)\(x\left(2x-1\right)\left(1-2x\right)=0\)
\(\Leftrightarrow-x\left(2x-1\right)\left(2x-1\right)=0\)
\(\Leftrightarrow-x\left(2x-1\right)^2=0\)
\(\Leftrightarrow\left[\begin{array}{nghiempt}-x=0\\\left(2x-1\right)^2=0\end{array}\right.\)
\(\Leftrightarrow\left[\begin{array}{nghiempt}x=0\\2x=1\end{array}\right.\)
\(\Leftrightarrow\left[\begin{array}{nghiempt}x=0\\x=\frac{1}{2}\end{array}\right.\)
PA
14 tháng 10 2016
\(2x^3+3x^2+2x+3=0\)
\(2x\left(x^2+1\right)+3\left(x^2+1\right)=0\)
\(\left(2x+3\right)\left(x^2+1\right)=0\)
\(2x+3=0\left(x^2+1\ge1>0\right)\)
\(2x=-3\)
\(x=-\frac{3}{2}\)
\(x\left(2x-1\right)\left(1-2x\right)=0\)
\(\left[\begin{array}{nghiempt}x=0\\2x-1=0\\1-2x=0\end{array}\right.\)
\(\left[\begin{array}{nghiempt}x=0\\2x=1\\2x=1\end{array}\right.\)
\(\left[\begin{array}{nghiempt}x=0\\x=\frac{1}{2}\end{array}\right.\)
IL
17 tháng 8 2016
Katherine Lilly Filbert nói rất đúng câu hỏi nhiều như vậy ai mà trả lời đc hết cơ chứ
12 tháng 8 2017
\(a,\)\(x^3-3x^2+1-3x\)
\(=\left(x^3+1\right)-\left(3x^2+3x\right)\)
\(=\left(x+1\right)^3-3x\left(x+1\right)\)
\(=\left(x+1\right)\left[\left(x+1\right)^2+3x\right]\)
\(=\left(x+1\right)\left(x^2+2x+1+3x\right)\)
\(=\left(x+1\right)\left(x^2+5x+1\right)\)
\(b,\)\(3x-7x-10\)
\(=3x^2+3x-10x-10\)
\(=\left(3x^2+3x\right)-\left(10x+10\right)\)
\(=3x\left(x+1\right)-10\left(x+1\right)\)
\(=\left(3x-10\right)\left(x+1\right)\)
\(c,\)\(x^4+1-2x^2\)
\(=x^4-x^2-x^2+1\)
\(=\left(x^4-x^2\right)-\left(x^2-1\right)\)
\(=x^2\left(x^2-1\right)-\left(x^2-1\right)\)
\(=\left(x^2-1\right)\left(x^2-1\right)\)
\(d,\)\(=x^2-3x+2\)
\(=x^2-x-2x+2\)
\(=\left(x^2-x\right)-\left(2x-2\right)\)
\(=x\left(x-1\right)-2\left(x-1\right)\)
\(=\left(x-2\right)\left(x-1\right)\)
B
21 tháng 8 2017
a,x2−y2−2x+2y=(x2−y2)−(2x−2y)=(x−y)(x+y)−2(x−y)=(x−y)(x+y−2). b,2x+2y−x2−xy=2(x+y)−x(x+y)=(x+y)(2−x)
c,3a2−6ab+3b2−12c2=3(a2−2ab+b2−4c2)=3.((a−b)2−(2c)2)
=3(a−b−2c).(a−b+2c)
d,x2−25+y2−2xy=(x2−2xy+y2)−52=(x−y)2−52
=(x−y+5)(x−y−5)
e,a2+2ab+b2−ac−bc=(a+b)2−c(a+b)=(a+b)(a+b−c)
ƒ ,x2
AT
1
\(\Rightarrow3\left(x^3-8\right)-3x^3-3x=-30\\ \Rightarrow3x^3-24-3x^3-3x=-30\\ \Rightarrow-3x=-6\Rightarrow x=2\)
\(3\left(x-2\right)\left(x^2+2x+4\right)-3x\left(x^2+1\right)=-30\)
\(\Leftrightarrow3x^2-24-3x^3-3x=-30\)
\(\Leftrightarrow x=2\)