Answer:
30...
Step-by-step explanation:
5*6=30
There are six digits to choose from, but you're only taking three at a time, so the number of such numbers is
The first and last digits can only be even if the number takes the one of the forms "2 _ 8" or "8 _ 2". The middle number can be any of the remaining four, so there is a total of eight such numbers.
This means the probability of getting a number beginning and ending with an even digits is
.
The quadratic formula is:
and
Let's identify our a, b, and c values:
a: -1
b: 1
c: 12
Plug in the values for a, b, and c into the equation. Let's do the first equation:
Simplify everything in the radical:
Simplify the radical:
Combine like terms:
Simplify:
This is one solution, now, let's solve for the other equation:
Since when simplified, everything is the same except the subtraction sign, we can skip the simplification again and change the sign to subtraction:
Combine like terms:
Simplify:
Your final answers are:
This number is an integer because it has a negative sign and all integers are negative