f.4quadratic equations

(x-k)(x-(k-1))=1(x - k)(x - k + 1) - 1 = 0(x - k)^2 + (x - k) - 1 = 0Let x - k be y ,y^2 + y - 1 = 0△ = 1^2 - 4(1)(-1) = 5 > 0So y = x - k have two distinct real values , therefore x have two distinct real values 。