Question

If
$(x { }^{2} + kx - 3) = (x - 3)(x + 1)$
then k= ?

Answer 1

$(x {}^{2} + kx - 3) = (x - 3)(x - 1) \\ x {}^{2} + kx - 3 = x {}^{2} - x - 3x + 3 \\ x {}^{2} + kx - 3 = x {}^{2} - 4x + 3 \\ x {}^{2} - ( - kx + 3) = x {}^{2} - ( 4x - 3)$
So, on equating LHS and RHS
k=4


---------Hope it helps--------