(x-3)√x^2+4<=x^2-9
x²-3x+4 ≤ x²-9 (√x²=x)
x²-x²-3x+4+9 ≤ 0
-3x+13 ≤ 0
-3x ≤ -13 | :(-3)
x ≥ 4,3 (3)
Ответ: