Square of sum: Complete the missing numbers

Fill in the blanks:

$x^2+\text{?}+9=(x+3)^2$

$6x$

Fill in the blanks:

$(x+?)^2=x^2+?+25$

$5,10x$

Fill in the blanks:

$(?\times x+?)^2=16x^2+32x+16$

$4,\text{ }4$

Complete what is missing:

$(2x+?\rparen^2=4x^2+16x+?$

4, 16

Fill in the blanks:

$(x^2+y)^2+(y^2+x)^2=?(x^2+1)+2xy\lbrack?\rbrack+y^2\lbrack?\rbrack$

$x^2,(x+y),y^2+1$

Solve for X:

$x+\sqrt{x}=-\sqrt{x}$

$0$