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Daca a+b=5 si a ori b = 4
Aflati a la a doua + b la a doua


Răspuns :

a^2+b^2=(a+b)^2-2ab=> 5^2-2*4=25-8=17
a + b = 5
ab = 4

Folosesti formula (a + b)² = a² + 2ab + b².

5² = a² + 2 · 4 + b²

25 = a² + b² + 8| -8

a² + b² = 17