Answer:
LCD= x²- 81
Step-by-step explanation:
x²-81 is difference of two squares
a²-b²= (a+b)(a-b)
x²- 81= (x+9)(x-9)
denominators, (x-9) and (x+9)(x-9)
x-9 is common in both denominators
x-9|(x-9)|(x+9)(x-9)
x+9| 1 | x+9
| 1 | 1
therefore the LCD= (x-9)(x+9)
simplifying= x²- 81
