Bài 1:
1.$(x+$ $\frac{1}{3})^{3}$$=x^{3}+3$ $x^{2}$ $\frac{1}{3}$+ $3x(\frac{1}{3})^{2}$+$(\frac{1}{3})^{3}=x^{3}+x^{2}$+$\frac{1}{3}x$+ $\frac{1}{27}$
2.$(2x+3y)^{2}=4x^2+2.2x.3y+9y^2=4x^2+12xy+9y^2$
3.$(3x-2y)^{2}=9x^2-12xy+4y^2$
4.$(3x^2-2y)^{2}=9x^4-12xy+4y^2$
5. $x^{2}-4y^2=(x-2y)(2y+x)$
6.$(2x^{}$ + $\frac{1}{2})^3$= $8x^{3}+3$. $4.x^{2}$ $\frac{1}{2}$+ $3.2x(\frac{1}{2})^{2}$+$(\frac{1}{2})^{3}=8x^{3}+6x^{2}$+$\frac{3}{2}x$+ $\frac{1}{8}$
7.$a^{6}-b^3=(a^2)^3-b^3=(a^2-b)(a^4+a^2b+b^2)$
8. $(x+y)^{2}-(2-y)^2=(x+y-2+y)(x+y+2-y)=(x+2y-2)(x+2)$
