Question 1064209
f(x) = -2x2 - 12x - 10 
Complete the square
-(2x^2+12x+10)=0
-(2x^2+12x)=10, remember, the 10 on the left side is minus.
-2(x^2+6x)=10
-2(x^2+6x+9)=-8, because you have to add -18 to both sides
-2(x+3)^2=-8
-2(x+3)^2+8=f(x)
The vertex is at (-3, 8)
when this equals 0, -2(x+3)^2=-8
(x+3)^2=4
x+3=+/- 2
x=-5 and -1
(-5,0) and (-1,0)
When x=0, y=-10
(0,-10)
{{{graph(300,300,-10,10,-10,10,-2x^2-12x-10)}}}