Question

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Answer 1

Răspuns:

Scriem totul in functie de a, deci:

b=(a*5)/2

c=(a*7)/2

Iar apoi inlocuim in relatia:

a+b+c=42

a+(a*5)/2+(a*7)/2=42

2*a+(a*5)+(a*7)=84

(a*7)+(a*7)=84

(a*14)=84

a=6

b=(a*5)/2

b=(6*5)/2

b=30/2

b=15

c=(a*7)/2

c=(6*7)/2

c=42/2

c=21

Answer 2

Răspuns:

a = 6

b = 15

c = 21

Explicație pas cu pas:

$\frac{a}{2} =\frac{b}{5} = \frac{c}{7} = k \\\\\frac{a}{2} = k =>a =2k\\\\\frac{b}{5} = k => b = 5k\\ \\\frac{c}{7} = k =>c= 7k\\\\a+b+c= 42\\\\2k + 5k + 7k = 42 =>14k = 42 =>k = 3\\\\a = 3* 2 => a = 6\\\\b= 3 * 5 =>b = 15\\\\c= 3 * 7 => c = 21$