Which expression is in simplified form for the given expression and states the correct variable restriction? u^2-4/(u-6)(u-2)
a. 1/u-3, u=3
b. u+2/u-6, u=2, u=6
c. 1/2u+12, u=-6
d. u+2/u-6, u=6

The computer that controls a bank's automatic teller machine crashes a mean of 0.6 times per day. what is the probability that, in any seven-day week, the computer will crash less than 5 times? round your answer to four decimal places