Question

Write the quadratic function in vertex form.

y = x2 + 8x + 18

Answer 1

i know you have to
Subtract 18 from both sides:
y - 18 = x^2 + 8x

Complete the square by adding 16 to both sides:
y - 18 + 16 = x^2 + 8x + 16
y - 2 = x^2 + 8x + 16

Express x^2 + 8x + 16 in binomial square form:
y - 2 = (x + 4)^2

Add 2 to both sides:
y = (x + 4)^2 + 2

Answer 2

You can use the vertex formula to figure out the max height:

t=−b2a

t=−6402(−16)

t=20

Next you'll need to insert t = 20 into the given equation:

h(20) = - 16(20)^2 + 640(20)

Answer 3

then simplify the expression on the right to solve for h(20)

Answer 4

how would you solve for h(20)

Answer 5

h(20) = - 16(20)^2 + 640(20)

Answer 6

@saseal

Answer 7

how did it turn from t into h?

Answer 8

i have no idea
im using this

Answer 9

http://openstudy.com/study#/updates/52586ec2e4b0ede9e4480f8b

Answer 10

ok the general form of a parabola looks like this \[x^2=4py\] and the standard forms are the messy quadratic equations

Answer 11

like that graph right?

Answer 12

\[x^2+8x+18=0\]since you cant factorize this you need to complete the square\[x^2+8x=-18\]\[x^2+8x+(\frac{ 8 }{ 2 })^2=-18+(\frac{ 8 }{ 2 })^2\]\[x^2+8x+16=-18+16\]\[(x+4)^2=-2\]

Answer 13

dont worry about that graph thing yet

Answer 14

ok

Answer 15

thank you

Answer 16

@nono266

Answer 17

you can understand it so far?

Answer 18

kinda

Answer 19

lol

Answer 20

that means you dont understand...

Answer 21

would it be - instead of the +

Answer 22

\[(x+4)^2=-2\]\[(x+4)^2+2=0\]

Answer 23

ugh yes!