Упростите выражение 5a(a+b+c)-5b(a-b-c)-5c(a+b-c).

\[5a(a + b + c) - 5b(a - b - c) - 5c \cdot\]

\[\cdot (a + b - c) = 5a^{2} + 5ab + 5ac - 5ab +\]

\[+ \ 5b^{2} + 5bc - 5ac - 5bc + 5c^{2} =\]

\[= 5a^{2} + \ 5b^{2} + 5c^{2}\]