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Daca x+2y=17 si y-3z=4, atunci calculati:
(2x+4y)*(x+4y-6z)
P.S: Vreau rezolvarea pas cu pas va rog.



Răspuns :

x+2y=17  x=17-2y
y-3z=4    z=(4-y)/3
(2(17-2y)+4y)×(17-2y+4y-3(4-y))
(34-4y+4y)×(17+2y-12-3y)
34×(5-y)=170-34y
34y=170⇒y=170/34=5
x+2y=17
x+2×5=17⇒x=17-10⇒x=7
y-3z=4