Question 847477
After doing some distributive property you'll end up with this result.

-dx^2-d+x^2+5x-1 = 0

Let's group the x^2,x, and constant terms together like this:

(1-d)x^2  +5x +(-1-d)

From there we can satisfy our discriminant {{{b^2-4ac >= 0}}}

{{{5^2 - 4(1-d)(-1-d) >=0}}}

{{{25 + 4(1-d^2) >= 0}}}

{{{25 + 4 - 4d^2 >=0}}}

{{{29 >= 4d^2}}}

{{{4d^2<= 29}}}

{{{d^2 <= 29/4}}}

{{{d <= 0 +- sqrt(29/4)}}} <--- sorry I have to put that 0 in or the +- doesn't show

{{{-sqrt(29)/2 <= d <= sqrt(29)/2}}}