Answer: a) 
Step-by-step explanation:
Given : For safety reasons, four different alarm systems were installed in the vault containing the safety deposit boxes at a Beverly Hills bank.
Each of the four systems detects theft with a probability of .99 independently of the others .
Probability for independent events
occurs together =
.
Then, the probability that when a theft occurs, all four systems will detect it
= (0.99) x (0.99) x (0.99) x (0.99)

Hence, the probability that when a theft occurs, all four systems will detect it is
.
Hence, the correct answer is a)
.
Answer: Choice C. (1, -6)
Explanation: The two lines cross at around this location. The solution point is on both lines at the same time.
There are no real roots for a negative number, so -81 has no real roots, if the number is 81 however, then the tow roots are 9
I believe the answer is d