Question : If $x + y + z = 19, x^2 + y^2 + z^2 = 133$ and $xz = y^2, x > z > 0,$ what is the value of $(x - z)$?

Question : If $x^4+x^2 y^2+y^4=21$ and $x^2+xy+y^2=3$, then what is the value of $4xy $?
 

Question : If $x$ and $y$ are real numbers, then the least possible value of $4 (x -2)^2+ (y-3)^2-2 (x-3)^2$ is:

Question : If $x+y+z=17, x y z=171$ and $x y+y z+z x=111$, then the value of $\sqrt[3]{\left(x^3+y^3+z^3+x y z\right)}$ is:

Question : (320 + 342 + 530 + 915) ÷ (20 + 22 – x + 18) = 43, then the value of $x$ is: