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a fost răspuns

Daca 2a+b=5 si 2b+3c=7 , calculati 4a + 8b + 9c.

Răspuns :

4a+8b+9c=(7+5)X2=12X2=24
[tex] 2a+b=5|*2 \\ 4a+2b=10 \\ 2b+3c=7|*3 \\ 6b+9c=21 \\ 4a+2b+6b+9c=10+21 \\ 4a+8b+9c=31[/tex]