(X^2)+13X+6.5=(-29.5) completing the square

We don't need to complete the square here, unless you want to.......

(x^2)+13x+6.5=(-29.5)     add 29.5 to both sides

x^2  + 13x + 36  =   0      factor

(x + 9) (x + 4)  = 0  

Set each factor to 0  and x = -9   or x = -4

x^2 +  13 x  + 6.5 = -29.5

x^2 + 13x             = - 36

x^2 + 13x  + 42.25  = - 36  + 42.25

(x+6.5)^2  =  6.25

x + 6.5  = sqrt 6.25 = +- 2.5

x = 2.5 - 6.5     or   -2.5 - 6.5

x= - 4          or     - 9