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Stiind ca 2a²+4ab-ab-2b²+ac+2bc=30 si a+2b=12, calculati 2a-b+c.
Please !


Răspuns :

Dai factor comun:
2a(a+2b)-b(a+2b)+c(a+2b)=30

(a+2b)(2a-b+c)=30
12(2a-b+c)=30

2a-b+c=[tex] \frac{30}{12} [/tex] = [tex] \frac{5}{2} [/tex]