<span><span>х^2 + у^2 + </span>z^2<span> = xy + xz + yz,у=7.Найти </span></span><span>x + y + z</span>
(x + y + z)²=
х^2 + у^2 + z^2 +2(
xy + xz + yz)
x + y + z= √(
х^2 + у^2 + z^2 +2( xy + xz + yz))=
√ 3( xy + xz + yz).
x + y + z =
√ 3( 7(x + z)+xz)
<span>
</span>