Question

convert x^2 -x -8 into vertex form

Answer 1

you know how to complete the square ?

Answer 2

factor?

Answer 3

whatst he co-efficient of x ?

Answer 4

for
\(x^2+bx+c\)
the co-efficient of 'x' is 'b'
so to complete the square, we add and subtract,
\((1/2)b^2\)

s, what do we add and subtract here ?

Answer 5

(1/2)1^2?

Answer 6

i mean (1/2)(-1)^2

Answer 7

which is just .5

Answer 8

sorry, i meant
\((1/2\times b)^2 = (-1/2)^2 =1/4\)

got this ?
add and subtract this!

Answer 9

\((x^2-x+1/4 ) + (-8-1/4)\)

Answer 10

now first 3 terms form a perfect square, can you figure out ?
\((..-..)^2\)

Answer 11

\((x- ...?...)^2 \)

Answer 12

ohh

Answer 13

umm

Answer 14

1/4 is the square of which number ?

Answer 15

1/2

Answer 16

(x-1/2)(x-1/2) ?

Answer 17

yes
correct!
so we have
\(\Large (x-1/2)^2 +(-1/4-8)\)

now just simplify
(-1/4-8)

Answer 18

-8.25

Answer 19

find in terms of fraction

Answer 20

-33/4?

Answer 21

thats right!
so your vertex form is just :
\(\Large (x-1/2)^2 -33/4\)
thats it! :)

Answer 22

omg! wow thanks so much

Answer 23

welcome ^_^