f(x) = ln(x² + 10x + 21) + √(64 - x²)
{(x + 3)(x + 7) > 0,
{(8 - x)(8 + x) ⩾ 0
{ x ∈ (-∞; -7) ∪ (-3; +∞),
{ x ∈ [-8; 8]
D(f) = [-8; -7) ∪ (-3; 8]
f(x) = ln(x² + 10x + 21) + √(64 - x²)
{(x + 3)(x + 7) > 0,
{(8 - x)(8 + x) ⩾ 0
{ x ∈ (-∞; -7) ∪ (-3; +∞),
{ x ∈ [-8; 8]
D(f) = [-8; -7) ∪ (-3; 8]