quick and simple maths problem - factorising (1 Viewer)

marann · Feb 19, 2009

hey guys.. i seem to have forgoton how to factorise? silly i know... can anyone help?
Factorise: -x^2 +9x -20

thank you

hermand · Feb 19, 2009

take the negative out of the equation
$-\left (x^{2}-9x+20 \right )$
$= - (x-5)(x-4)$
the -5 & -4 add to make -9 and multiply to make 20.

x3.eddayyeeee · Feb 19, 2009

(-x+5)(x-4)

= -x^2 + 4x + 5x - 20

= -x^2 + 9x - 20

EDIT. ^Poster above beat me to it.

duckcowhybrid · Feb 19, 2009

The answer is

(x - 4)(-x + 5)

Really how can't you do that.

dux&src · Feb 19, 2009

Everyone is right here

Aerath · Feb 19, 2009

duckcowhybrid said:
The answer is

(x - 4)(-x + 5)

Really how can't you do that.

Not everyone is as mathematically talented as you are.

tommykins · Feb 20, 2009

Aerath said:
Not everyone is as mathematically talented as you are.

haha please don't call him talented.