Answer:
x=-10 x=4
Explanation:
y = -x^2 - 6x + 40
To find the x intercepts set y =0 and solve for x
0 = -x^2 - 6x + 40
Divide by -1
0 = x^2 + 6x - 40
What two numbers multiply to -40 and add to 6
10*-4 = -40
10 -4 = 6
(x+10) (x-4) =0
Using the zero product property
x+10 =0 x-4=0
x+10-10=0-10 x-4+4=0+4
x=-10 x=4