If $x^2+k(4x+k-1)+2=0$ has equal roots, then the possible values of $k$ are

If$\sin \alpha$ and $\cos \alpha$ are the roots of the equation $a{x}^2+bx+c=0$, then $b^2=$

If $2$ is a root of the equation $x^2 +ax+12=0$ and the quadratic equation $x^2 +ax+q=0$ has equal roots, then $q$ is equal to

A quadratic equation whose one root is$2$ and the sum of whose roots is zero, is

If one of the root of the equation $2x^2+kx+4=0$ is $2$, then the other root is