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a fost răspuns

Daca x/2 = y/3 = z/5 si 3x+2y-z =21 , atunci .
a ) Aflati nr x,y,z .
b) cat la suta reprezinta x din y+z ?
c ) verificati ca ( x+y+z ) la a doua = x la a doua + y la a doua + z la adoua + 2xy + 2xz + 2yz , pentru valorile x,y,z determinate mai sus .

Răspuns :

Tall12
a)x/2=y/3=z/5=k(k≠0)
x=2k
y=3k
z=5k
3x+2y-z=21
6k+6k-5k=21
7k=21
k=3⇒x=6
y=9
z=15
b)y+z=9+15=24
p%·6=24
p%=4
p=400
(x+y+z)²=x²+y²+z²+2xy+2xz+2yz
(6+9+15)²=36+81+225+2·54+2·90+2·135
30²=117+225+108+180+270
900=342+108+450
900=450+450
900=900(A)