Question

Dacă a+b=45 și a/c+b/c=450, calculează 3/a+3/b+3/c

Answer 1

$a+b=45; \frac{a}{c}+ \frac{b}{c} =450 \\ \frac{a+b}{c}=450; \frac{45}{c}=450 \\ c= \frac{1}{10} \\ \frac{3}{a}+ \frac{3}{b}+ \frac{3}{c}= 3(\frac{1}{a}+ \frac{1}{b}+ \frac{1}{c})=3( \frac{a+b}{ab}+10)=3( \frac{45}{ab} +10)$