Question

x+y+z, stiind ca x,y,z apartine R+,si x²+y²+z²=124 si xy+yz+xz=66.
va rog rapid

Answer 1

exista formula (a+b+c)²=a²+b²+c²+2ab+2bc+2ac

in cazul nostru
(x+y+z)²=
=x²+y²+z²+ 2xy+2yz+2xz=
=x²+y²+z²+ 2(xy+yz+xz)=
=124+2×66=
=124+132=256

x+y+z=√256=16