Question

Un fermier creste pasari si vitei ‚ in total 115 capete si 260 picioare. Cate pasari si cati vitei creste fermierul?? Trebuie rezolvata prin ECUATIE...

Answer 1

a=pasari , b=vitei
a+b=115
2a+4b=260
a=115-b
2(115-b)+4b=260
230-2b+4b=260
2b=260-230
b=30:2
b=15 vitei
a=115-15=100 pasari

Answer 2

$x\to nr. \ pasarilor \\ y\to nr. \ viteilor \\\\ \left \{ {{x+y=115} \ |(-2) \atop {2x+4y=260}} \right. \\\\\\ \left \{ {{-2x-2y=-230} \atop {2x+4y=260}} \right. \\========== \\ / \ \ \ 2y=30 \ |:2 \\\\ \boxed{y=15} \\\\ x+y=115 \\\\ x=115-y \\\\ x=115-15 \\\\ \boxed{x=100}$
     
                                                    OR

$x \to nr. \ pasarilor \\ y \to nr. \ viteilor \\\\ x+y=115 \ \ \ \ \to \boxed{x=115-y} \\\\\\ 2x+4y=260 \\\\ 2(115-y)+4y=260 \\\\ 230-2y+4y=260 \\\\ 2y=260-230 \\\\ 2y=30 \ |:2 \\\\ \boxed{\boxed{y=15}} \\\\ x=115-15 \\\\\\ \boxed{\boxed{x=100}}$