#What are the roots of the equation x² - 4x - 5 = 0?

16 messages · Page 1 of 1 (latest)

thin stirrup
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x=-1
x=5

lavish pumice
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do you know how to factor quadratic equations?

keen mica
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Yes

lavish pumice
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what is x^2-4x-5 in its factored form?

keen mica
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(x -5) (x +1)

lavish pumice
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so we have 0=(x-5)(x+1)

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the good thing about factored form is that we can easily see the solution of the equation

keen mica
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Ohh okok now I get it

lavish pumice
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by equating one of the term to 0 ( as the other gets cancelled out by multiplying by 0)

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so suppose 0=x-5

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let x = 5

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0=(5-5)(5+1)

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0=0*6=0

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and the same for x=-1

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(-1-5)(-1+1) = -6*0 = 0

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hence our solution is x=5 and x=-1