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2014-04-21T13:26:23+03:00
Metoda 1(substituție)

 \frac{a}{b}= \frac{5}{2}   \\ a= \frac{5b}{2} \\ 4a^2+25b^2=4( \frac{5b}{2})^2+25b^2=4* \frac{25b^2}{4}+25b^2=50b^2= \frac{5b}{2}*20b=20ab     (Adevărat)

Metoda 2(mai deșteaptă)

 \frac{a}{b}= \frac{5}{2} \\ 2a=5b \\ 4a^2+25b^2=20ab \\ 4a^2-20ab+25b^2=0 \\ (2a-5b)^2=0 \\ 2a-5b=0 \\  2a=5b
(Adevărat)
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