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How do you solve $(20-r)^(1/2)=r$ ?

1 Answer

Aug 2, 2016

$r= 4 or -5$

Explanation:

$(20-r)^(1/2) = r$

$sqrt(20-r) = r$

Square both sides:
$20-r=r^2$

$r^2+r-20=0$

Factorise:
$(r-4)(r+5)=0$

$r = 4 or -5$

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