<PRE><B>Question 196350</B>
10 x^2 +kx +8 =0
.
divide  by  10
.
x^2 + (k/10)x + 8/10  =0
.
To  get  one  equal  answer,  we  must  have  sums  squared,  (x+a) (x+a) =0,
To  complete  the  square,  the  coefficient  of  the  2nd  term  is  halved  and  then squared
to  equal  the  third  term
.
(k/(2*10))^2 = 8/10
k^2/400  = 8/10
k^2 = 320
k= +/- 17.88,,,,(8sqrt5)
.
checking
10 x^2 +(17.88)x +8 =0
x^2 +1.788 x +.8 =0
(x+sqrt.8)(x+sqrt.8)  =0
(x +.894) (x+.894) =0
x= -.894, -.894,,,  ok
.
checking  with  k=-17.887,,,,,finds  the  same,,  except  x= +.894, +.894  ,,,ok</PRE>