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e)
$x^3+6x^2+12x+8=x^3+3.2.x^2+3.2^2.x+2^3=(x+2)^3$
f)
$a^3-2a^2-ab^2+2b^2=(a^3-ab^2)-(2a^2-2b^2)$
$=a(a^2-b^2)-2(a^2-b^2)=(a^2-b^2)(a-2)=(a-b)(a+b)(a-2)$
g)
$2a^2x-2a^2-2abx+4ab-2b^2=(2a^2x-2abx)-(2a^2-4ab+2b^2)$
$=2ax(a-b)-2(a-b)^2=2(a-b)(ax-a+b)$
h)
\(x^2-2xy+y^2-25=(x-y)^2-25=(x-y)^2-5^2=(x-y+5)(x-y-5)\)
a)
$4x^2-40x^4+100x^3=4x^2(1-10x^2+25x)$
b)
\(3xy(x-5)-7x+35=3xy(x-5)-7(x-5)\)
\(=(x-5)(3xy-7)\)
c)
\(a^2-am-b^2-bm=(a^2-b^2)-(am+bm)=(a-b)(a+b)-m(a+b)\)
\(=(a+b)(a-b-m)\)
d)
\(x^3-4x-x^2y+4y=(x^3-x^2y)-(4x-4y)\)
\(=x^2(x-y)-4(x-y)=(x^2-4)(x-y)=(x-2)(x+2)(x-y)\)
Bạn làm bài kiểm tra hả sao nhiều bài tek. Mk làm mất khá nhiều tg luôn đó 
Có một số câu thì mình không làm được. Mong bạn thông cảm!!!
a)\(x^2+7x+6\)
\(=x^2+6x+x+6\)
\(=x\left(x+6\right)+\left(x+6\right)\)
\(=\left(x+1\right)\left(x+6\right)\)
b)\(x^4+2016x^2+2015x+2016\)
\(=x^4+2016x^2+\left(2016x-x\right)+2016\)
\(=\left(x^4-x\right)+\left(2016x^2+2016x+2016\right)\)
\(=x\left(x-1\right)\left(x^2+x+1\right)+2016\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left(x^2-x+2016\right)\)
Bài 3:
Từ \(a^2+b^2+c^2+3=2\left(a+b+c\right)\)
\(\Rightarrow a^2+b^2+c^2+3-2a-2b-2c=0\)
\(\Rightarrow\left(a^2-2a+1\right)+\left(b^2-2b+1\right)+\left(c^2-2c+1\right)=0\)
\(\Rightarrow\left(a-1\right)^2+\left(b-1\right)^2+\left(c-1\right)^2=0\) (1)
Ta thấy:\(\begin{cases}\left(a-1\right)^2\ge0\\\left(b-1\right)^2\ge0\\\left(c-1\right)^2\ge0\end{cases}\)
\(\Rightarrow\left(a-1\right)^2+\left(b-1\right)^2+\left(c-1\right)^2\ge0\) (2)
Từ (1) và (2) \(\Rightarrow\begin{cases}\left(a-1\right)^2=0\\\left(b-1\right)^2=0\\\left(c-1\right)^2=0\end{cases}\)
\(\Rightarrow\begin{cases}a-1=0\\b-1=0\\c-1=0\end{cases}\)\(\Rightarrow\begin{cases}a=1\\b=1\\c=1\end{cases}\)
\(\Rightarrow a=b=c=1\Rightarrow H=1\cdot1\cdot1+1^{2014}+1^{2015}+1^{2016}=1+1+1+1=4\)
A, x2+3x+7 = x2+2.x.3/2 +(3/2)2+19/4 = (x+3/2)2 + 19/4 >=19/4
B, = (x2-7x+10)(x2-7x-10) = (x2-7x)2 - 100 >= -100
C, = 5x2+5 >=5
1. \(4x^2-2x-3y-9y^2\)
\(=\left(2x\right)^2-\left(3y\right)^2-\left(2x+3y\right)\)
\(=\left(2x-3y\right)\left(2x+3y\right)-\left(2x+3y\right)\)
\(=\left(2x+3y\right)\left(2x-3y-1\right)\)
2. \(x^2-25=6x-9\)
\(\Rightarrow x^2-6x+9=25\)
\(\Rightarrow\left(x-3\right)^2=25\)
\(\Rightarrow\orbr{\begin{cases}x-3=5\\x-3=-5\end{cases}}\Rightarrow\orbr{\begin{cases}x=8\\x=-2\end{cases}}\)
\(a,6x^2-9x=3x\left(x-3\right)\)
\(b,x^3-2x^2-3x+6\)
\(=\left(x^3-2x^2\right)-\left(3x-6\right)\)
\(=x^2\left(x-2\right)-3\left(x-2\right)\)
\(=\left(x^2-3\right)\left(x-2\right)\)
\(e,2x\left(x-y\right)-3y\left(x-y\right)\)
\(=\left(2x-3y\right)\left(x-y\right)\)
a) 6x2 - 9x
= 3x (2x - 3)
b) x3 - 2x2 - 3x + 6
= x2(x - 2) - 3 (x - 2)
=(x - 2) (x2 - 3)
c) x2 - 4x + 4 - 9y2
= (x - 2)2 - 9y2
=(x - 2 - 3y)(x - 2 + 3y)
e) 2x(x - y) - 3y(x - y)
= (x - y)(2x - 3y)
xin lỗi mình học ngu nên không biết làm nhìu nha
b, A=[(a+1)(a+7)][(a+3)(a+5)]+15
=>A=(a2+8a+7)(a2+8a+15)+15
Đặt a2+8a+11= t
=>a2+8a+7= t-4 và a2+8a+15= t+4
=>A=(t-4)(t+4)+15
=>A=t2-16+15
=t2-1=(t-1)(t+1)
Thay t = a2+8a+11
=>A=(a2+8a+11-1)(a2+8a+11+1)
=>A=(a2+8a+10)(a2+8a+12)
a) \(x^2+2xy+7x+7y+y^2+10\)
\(=\left(x+y\right)^2+7\left(x+y\right)+\frac{49}{4}-\frac{9}{4}\)
\(=\left(x+y+\frac{7}{2}\right)^2-\frac{9}{4}\)
\(=\left(x+y+\frac{7}{2}-\frac{3}{2}\right)\left(x+y+\frac{7}{2}+\frac{3}{2}\right)\)
\(=\left(x+y-2\right)\left(x+y+5\right)\)