Question 190630
Find d if {{{y^2-10y+d}}} is a perfect square:
In order for {{{y^2-10y+d}}} to be a perfect square, d must be the square of half the y-coefficient, or {{{(10/2)^2 = highlight(25)}}}, so....
{{{y^2-10y+25 = (y-5)^2}}}