(5.y)^2-20=0
=> (5.x)^2 = 0 + 20
=> (5.x)^2 = 20
=> sai đề
\(\left(5y\right)^2-20=0\)
\(\Rightarrow5y=\sqrt{20}\)
\(\Leftrightarrow y=\frac{\sqrt{20}}{5}=\frac{2\sqrt{5}}{5}\)
(5y)^2-20=0
<=>(5y)^2=20
<=>5 y= căn 20
<=>y= căn 20/5
y=-2/căn bậc hai(5), y=2/căn bậc hai(5)
(5.y)^2-20=0
(5.y)^2=20.................................!
chac sai de roi ban a!
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