If $$ {\sqrt{2x+9}+x=13}$$ then find the value of x?

If 0.4 m + 0.8 n = 2.2 and 0.8 m + 0.4 n = 1.4, then the value of $$ {m^2}+{n^2}$$ is equal to 

If x + y + z=1, xy+yz+zx=-26 and x³ + y³+z³=151, then what will be the value of xyz?

If  $$\sqrt{a}+\sqrt{b}=15 \ and \ (\sqrt{a}-\sqrt{b} )=3$$ then the value of $$\sqrt{ab/4} $$ is 

If $$ {x^{12}+x^{3}\over {x^{6}}}=0$$ find $$ {x^{36}+{1\over x^{36}}}$$

If x + y = 1 and xy (xy – 2) = 12,then the value of x⁴ + y⁴ is:

If $$ x=\sqrt{\sqrt{5}+1\over {\sqrt{5}-1}}$$ then the value  of $$ {5x^2-5x-1}$$ will be:

If xy(x+y)=1, then $$ {1\over x^3 y^3}-{x^3-y^3}$$ is equal to-