The number of ways of choosing 4 digits from 10 digits without replacement ( order is important) is
. This is the number of all possible permutations of choosing 4 from 10. The first 4 numbers of your phone number is a unique 4 digit number(4 different digits). The required probability is

Answer:
c = –13
Step-by-step explanation:
by property of tangent line, equation
x² – x – 12 = x + c
x² – 2x – 12 – c = 0
has only one solution, which mean
– 12 – c = 1
c = –13
Answer:
2/5
Step-by-step explanation:
The experimental probability is
P (heads) = number of heads/ total tosses
= 8/20
= 2/5