Zadanie z załaczniku. Poprawna odpowiedź to B. Jak do tego dojść?
l=r+2
πrl=15π
r=15/l
l=15/l+2
l²=15+2l
l²-2l-15=0
l²-5l+3l-15=0
l(l-5)+3(l-5)=0
(l+3)(l-5)=0
l=-3 ∨ l=5
l=5 ⇒ B
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l=r+2
πrl=15π
l=r+2
r=15/l
l=15/l+2
l²=15+2l
l²-2l-15=0
l²-5l+3l-15=0
l(l-5)+3(l-5)=0
(l+3)(l-5)=0
l=-3 ∨ l=5
l=5 ⇒ B