How do you solve #r^ { 2} - 9r + 20= 0#?

1 Answer
Tony B
Dec 13, 2016

#x=+4" and "x=+5# are solutions to #r^2-9r+20=0#

Explanation:

Note that #4xx5=20" and that "color(red)(-4)color(green)(-5)=-9#

So we have the factorisation of #" (xcolor(red)(-4))( xcolor(green)(-5))=0#

so #x=+4" and "x=+5# are solutions to #r^2-9r+20=0#

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