Leo núi

 $(A+B)^2=A^2+2AB+B^2$ 

 $(A+B)^2=A^2+AB+B^2$ 

 $(A+B)^2=A^2+B^2$ 

 $(A+B)^2=A^2–2AB+B^2$ 

 $(A–B)(A+B)=A^2+2AB+B^2$ 

 $(A+B)(A–B)=A^2–B^2$ 

 $(A+B)(A–B)=A^2–2AB+B^2$ 

 $(A+B)(A–B)=A^2+B^2$ 

 $(x+y)^2=(x+y)(x+y)$ 

 $x^2–y^2=(x+y)(x–y)$ 

 $(-x–y)^2=(-x)^2–2(-x)y+y^2$ 

 $(x+y)(x+y)=y^2–x^2$ 

 $(x+2y)^2=x^2+4xy+4y^2$ 

 $(x–2y)^2=x^2–4xy+4y^2$ 

 $(x–2y)^2=x^2–4y^2$ 

 $(x–2y)(x+2y)=x^2–4y^2$ 

 $(4x–5y)(4x+5y)$  

 $(4x–25y)(4x+25y)$  

 $(2x–5y)(2x+5y)$  

 $(2x–5y)^2$  

 $\left(\frac{x}{9}-\frac{y}{64}\right).\left(\frac{x}{9}+\frac{y}{64}\right)$  

 $\left(\frac{x}{3}-\frac{y}{4}\right)\ \left(\frac{x}{3}+\frac{y}{4}\right)$  

 $\left(\frac{x}{9}-\frac{y}{8}\right)\left(\frac{x}{9}+\frac{y}{8}\right)$  

 $\left(\frac{x}{3}-\frac{y}{8}\right)\left(\frac{x}{3}+\frac{y}{8}\right)$  

 $A.9x^2–24xy+16y^2$  

 $B.9x^2–12xy+16y^2$  

 $C.9x^2–24xy+4y^2$  

 $D.9x^2–6xy+16y^2$  

 $\frac{x^2}{4}-xy+4y^2$  

 $\ \frac{x^2}{4}-2xy+4y^2$  

 $\ \frac{\ x^2}{4}-2xy+2y^2$  

 $\frac{x^2}{2}-2xy+2y^2$  

 $\left(\frac{1}{4}xy+1\right)^2$  

 $\left(\frac{1}{2}xy+1\right)^2$  

 $\left(xy-\frac{1}{2}\right)^2$  

 $\left(\frac{1}{2}xy-1\right)^2$  

 $(5x–2y)^2$  

 $(2x–5y)^2$  

 $(25x–4y)^2$  

 $(5x+2y)^2$