Question 816274
<pre>
x²+39x+360 = 0

It can be factored:

(x+24)(x+15) = 0

x+24=0;  x+15=0
  x=-24;    x=-15

But you could have solved it using the quadratic formula.

You got the quadratic formula wrong and used b²-4bc instead of b²-4ac.

{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}} 

{{{x = (-39 +- sqrt( 39^2-4*1*360 ))/(2*1) }}}

{{{x = (-39 +- sqrt(1521-1440 ))/2 }}}

{{{x = (-39 +- 9)/2 }}}

Using the +


{{{x = (-39 + 9)/2 }}}


{{{x = (-30)/2 }}}

x = -15   


Using the -


{{{x = (-39 - 9)/2 }}}


{{{x = (-48)/2 }}}

x = -24   

Edwin</pre>