There are 2 roots so the only way to complete the square is,
![y=2x^2+8x-9\\y=2[(x^2+4x)]-9\\y=2[(x^2+4x+4)-4]-9\\y=2[(x+2)^2-4]-9\\y=2(x+2)^2-8-9\\y=2(x+2)^2-17](https://tex.z-dn.net/?f=y%3D2x%5E2%2B8x-9%5C%5Cy%3D2%5B%28x%5E2%2B4x%29%5D-9%5C%5Cy%3D2%5B%28x%5E2%2B4x%2B4%29-4%5D-9%5C%5Cy%3D2%5B%28x%2B2%29%5E2-4%5D-9%5C%5Cy%3D2%28x%2B2%29%5E2-8-9%5C%5Cy%3D2%28x%2B2%29%5E2-17)
Just factor 2 out of 2x^2+8x (just ignore the -9) then find the number that will make the terms be able to complete the square.
then complete the square and multiply 2 inside the brackets.
subtraction as you already get the vertex form and know how to complete the square.
Vertex Form: 
Mathematically written:
3 * x + 7 = 25
3x + 7 = 25
3x = 25 - 7
3x = 18
x = 18 / 3
x = 6
Proof:
3 * 6 + 7 = 25
18 + 7 = 25
25 = 25 → both sides of the equation are equal, our answer is correct
Notes:
A number - Is an unknown number, called a variable, which in this case is substituted by the letter x.
Hope it helped,
BioTeacher101
Answer:
Step-by-step explanation:
What variable are you solving for?
Answer:
i think its number 2 hope its correct
Nearest tenths - 8.5
Nearest hundredths- 8.55
