Solve the equation by factorisation: $9x^2-9\left(a+b\right)x+\left(2a^2+5ab+2b^2\right)=0$.

Solve the equation by factorisation: $12ab{x}^2-\left(9a^2-8b^2\right)x-6ab=0$.

Solve the equation by factorisation: $\frac{1}{2a+b+2x}=\frac{1}{2a}+\frac{1}{b}+\frac{1}{2x}$.

Solve the quadratic equation by completing the square:

$x^2-4x-1=0$

Solve the quadratic equation by completing the square:

$x^2-4\sqrt{2}x+6=0$

Solve the quadratic equation by completing the square:

${2x}^2-3x-1=0$

Solve the quadratic equation by completing the square:

${2x}^2+x+4=0$

Solve the quadratic equation by completing the square:

${4x}^2-8x+1=0$

Solve the quadratic equation by completing the square:

${\sqrt{2}x}^2-3x-2\sqrt{2}=0$