Well u need to give me the equation and the substitutions for the variables then I can solve it
Consider expression 
1. Use property

Then

2. Use property

Then

3. Use property

Then

4. Use property

Then

Answer: correct option is B.
Answer: 5^(-18)
Step by step solution: See photo
Just multiply them together and get a4-2a2-24.
(a2-6)(a2+4)
F: a4
O:4a2
I:-6a2
L:-24
Add together
a4-2a2-24