Question 390071
Put x = -2 into the equation:  {{{2*(-2)^2 + 10*-2 + k = 0}}} ====> 8 - 20 + k = 0, or -12 + k = 0, or k = 12.  The equation is then {{{2x^2 + 10x + 12 = 0}}}.  The equation simplifies to {{{x^2 + 5x + 6 = 0}}}, which is the same as (x + 2)(x+3)=  0, so the other root is -3.