Question

Increasing and decreasing intervals of 4x^2+4x-1

Answer 1

do you know derivatives?

Answer 2

we have to complete the square

Answer 3

would it be \[\huge 4x^2+4x-4+4-1 \] for the first step of completing the square ?

Answer 4

yes

Answer 5

then \[\huge 4 (x-1)^2 -1\] ? :S

Answer 6

when you multiply that out it doesnt give you 4x^2+4x-4+4-1

Answer 7

try this one 4(x+(1/2))^2 -2

Answer 8

i dont get where the 1/2 comes from :S

Answer 9

i found the error: the leading coefficient must be 1 to complete the square
try setting it equal to 0, moving the -1 over, and dividing by 4
then complete the square

Answer 10

why does it have to be 1 ?

Answer 11

because thats what the formula says

Answer 12

oh so it applies at all equations ?

Answer 13

it applies to quadratics with a leading coefficient of 1