SOLUTION: Given the quadratic function f(x) = -2x2 - 12x - 10 a. Use “completing the squares” to convert the quadratic function into vertex form b. State the vertex c. Find the x- and

Algebra ->  Rational-functions -> SOLUTION: Given the quadratic function f(x) = -2x2 - 12x - 10 a. Use “completing the squares” to convert the quadratic function into vertex form b. State the vertex c. Find the x- and       Log On


   



Question 1064209: Given the quadratic function f(x) = -2x2 - 12x - 10
a. Use “completing the squares” to convert the quadratic function into vertex form
b. State the vertex
c. Find the x- and y-intercepts
d. Graph the function

Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
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%28300%2C300%2C-10%2C10%2C-10%2C10%2C-2x%5E2-12x-10%29