Answer:

x≤4 or x≥9; in interval notation: (-∞,4]∪[9,∞)

Step-by-step explanation:

Solve x²-13x+36=0 to find "boundary numbers". This will give you 3 intervals of numbers to check: <4, between 4 & 9, and >9.

Test a number from each interval to see if it makes a "true" inequality. I chose 0, 5, and 10. Ex: (0)²-13(0)+36>0; (5)²-13(5)+36<0; etc.