Giải pt:
1)$(a+b+x)^{3}-4(a^{3}+b^{3}+x^{3})-12abx=0$
2)$(8x-4x^{2}-1)(x^{2}+2x+1)=4(x^{2}+x+1)$
3)$4x^{3}+3x=\frac{3}{4}$
4)$6x^{4}+8x^{2}+6=(x^{4}+2x^{2}+1)(1+4y-y^{2})$
5)$8x^{3}+6x=\frac{8}{3}$
6)$32x^{4}+(4x-1)^{4}=\frac{1}{27}$
7)$x^{4}+y^{4}+(x^{2}+y^{2}-2)(2xy-1)+3x^{2}y^{2}-1=0$