# Math Help - er quadratic fatorisation?

Any help on this would be appreciated...

write $4x^2 - 24x + 27$ in the form $a(x-b)^2+c$

i have thought about factorising but it wants the $+ c$ which just confuses me

thanks

2. Originally Posted by RubbishAtMaths
Any help on this would be appreciated...

write $4x^2 - 24x + 27$ in the form $a(x-b)^2+c$

i have thought about factorising but it wants the $+ c$ which just confuses me

thanks

$y=4x^2-24x+27$

$y-27=4x^2-24x$

$y-27=4(x^2-6x)
$

$y-27=4(x^2-6x+9-9)$

$y-27=4(x-3)^2-4(9)$

$y=4(x-3)^2-9$

Edit: Moo beat me to it!

3. Hello,
Originally Posted by RubbishAtMaths
Any help on this would be appreciated...

write $4x^2 - 24x + 27$ in the form $a(x-b)^2+c$

i have thought about factorising but it wants the $+ c$ which just confuses me

thanks
$4x^2-24x+27=4(x^2-6x)+27=4[(x-3)^2-3^2]+27$
$=4(x-3)^2-4 \cdot 3^2+27=4(x-3)^2-9$

4. how do you go about completing the square?

*thanks moo!

5. Originally Posted by RubbishAtMaths
how do you go about completing the square?

*thanks moo!
\

6. ## could u just explain this a little please

i understand most of it just not the bit i have pointed out
Originally Posted by TheMasterMind
$y=4x^2-24x+27$

$y-27=4x^2-24x$

$y-27=4(x^2-6x)
$

$y-27=4(x^2-6x+9-9)$

$y-27=4(x-3)^2-4(9)$
I dont Understand what u did with the -27 and how u got the -4(9)???
thanks
$y=4(x-3)^2-9$

Edit: Moo beat me to it!

$y-27=4(x-3)^2-9(4)$
$y-27=4(x-3)^2-36$
$y=4(x-3)^2-36+27$
$y=4(x-3)^2-9$