Is there a good way to always know how to split the middle term of a quadratic equation like x^2-9x+20=0?

It turns out that -5x and -4x "works" but is there a better way to split the term that is less tedious?

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- Aug 9th 2011, 04:33 PMhappyfaceFactoring Quadratic Equations -- Splitting the Middle Term
Is there a good way to always know how to split the middle term of a quadratic equation like x^2-9x+20=0?

It turns out that -5x and -4x "works" but is there a better way to split the term that is less tedious? - Aug 9th 2011, 04:38 PMPlatoRe: Factoring Quadratic Equations -- Splitting the Middle Term
- Aug 9th 2011, 04:43 PMhappyfaceRe: Factoring Quadratic Equations -- Splitting the Middle Term
I see! Negative 4 and 5 equal 9 when added, and 20 when multiplied.

There are a few cases (like ax^2 + bx + c) where it is not so obvious where to split the middle term. That is especially where I get stumped, since c does not always equal the product of the "split" term.

Thats actually what I meant to ask about. - Aug 9th 2011, 04:51 PMPlatoRe: Factoring Quadratic Equations -- Splitting the Middle Term
- Aug 9th 2011, 05:50 PMhappyfaceRe: Factoring Quadratic Equations -- Splitting the Middle Term
Thanks! Very helpful.