\frac{P_1}{P_2}=k^2
\frac{x}{y}=k^2
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x+y=800
\frac{x}{y}=3^2
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y=800-x
\frac{x}{800-x}=9
x=9(800-x)
x=7200-9x
x+9x=7200
10x=7200 |:10
x = 720 cm^2
y=800-720
y = 80 cm^2
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sprawdzenie:
\frac{P_1}{P_2}=\frac{720}{80}=9=3^2=k^2