Hey there!
Let me help you will quick...
So, we have:
[tex]40=-x^2 -14x
[/tex]
Start by subtracting [tex]-x^2 -14x [/tex] from both sides
[tex]40-(-x^2 -14x)=-x^2 -14x-(x^2 -14x)
x^2 +14x +40 = 0 [/tex]
Now we need to factorize [tex](x+4)(x+10)=0
Set factors equal to 0
x+4 = 0 or x+10 =0
x = 0 - 4 or x = 0 - 10
x = -4 or x=-10[/tex]
Best of luck with your studies!