$2x\left(x^2+3x-5\right)=$  

 $\$  $-4x\left(5-6x\right)$  

(A + B)(C - D) =

 $\left(x-1\right)\left(x^2+x+1\right)=\$  

 $\left(x+5\right)^2=\ x^2+5x+25\ là\ đúng\ hay\ sai?$  

 $\left(x-7\right)^2=\ x^2-14x+49\ là\ đúng\ hay\ sai?$  

 $\left(x-2\right)^3=\ x^3-6x^2+6x-8\$  

 $\left(3-x\right)^3=27-27x^{ }+9x^2-x^3\$  

 $x^2-81\ =\$  

 $\ x^3\ -64\ =\ \left(x-4\right)\left(x^2-4x+16\right)$  

 $\ x^3\ +64\ =\ \left(x+4\right)\left(x^2-4x+16\right)$  

 $\ \ \left(x+5\right)\left(x^2-5x+25\right)\ =\ x^3-125$  

 $\ \ \left(x-5\right)\left(x^2+5x+25\right)\ =\ x^3-125$  

 $\ \ a^2-2a+1\ =\left(a-1\right)^2\$  

 $\ \ a^2+9-6a\ \ =\left(a+3\right)^2\$  

 $\ \ 25x^2-20xy\ +4y^2\ \ =\left(5x-4y\right)^2\$  

 $\ \ x^3+8\ =\left(\ x+2\right)\left(x^2-2x+4\right)$  

 $\ \ x^3+6x^2+12x\ +8\ =\left(x+8\right)^3$  

 $\ \ x^3+3x^2y+3xy^2\ +y^3\ =\left(x+y\right)^3$