WILL GIVE BRAINLIEST! Alice, Bob, and Carrie can all choose a number from 1 to 10 (inclusive). (a) Find the number of ways they can choose their numbers if all three numbers are different.

(b) Find the number of ways they can choose their numbers if they have to choose exactly two different numbers among all three people. (For example, Alice and Bob both pick 1, and Carrie picks 2.)

(a) 720

(b) 180

Step-by-step explanation:

We are given 10 numbers (1,2,3,4,.....,10).

(a) 3 unique numbers are to be chosen by Alice, Bob and Carrie.

Number of ways to choose the 1st number = 10

Number of ways to choose the 2nd number = 9 (1 number chosen earlier can't be chosen again)

Number of ways to choose the 3rd number = 8 (2 numbers chosen earlier can't be chosen again)

Total number of ways of choosing 3 unique numbers =

(b)

Number of ways of choosing 1st number = 10 (no restrictions)

Number of ways of choosing 2nd number = 9 (1 number chosen earlier can't be chosen again)

Now, restriction on the 3rd number to be chosen is that one of the two already chosen number should be chosen again.

So, number of ways to choose 3rd number = 2

the number of ways they can choose their numbers if they have to choose exactly two different numbers among all three people =

Hence, the answers are:

(a) 720

(b) 180

14

step-by-step explanation:

{x = -1/2 ,   y = -1

step-by-step explanation:

solve the following system:

{2 x + y = -2

{10 x - 3 y = -2

in the first equation, look to solve for y:

{2 x + y = -2

{10 x - 3 y = -2

subtract 2 x from both sides:

{y = -2 x - 2

{10 x - 3 y = -2

substitute y = -2 x - 2 into the second equation:

{y = -2 x - 2

{10 x - 3 (-2 x - 2) = -2

10 x - 3 (-2 x - 2) = (6 x + 6) + 10 x = 16 x + 6:

{y = -2 x - 2

{16 x + 6 = -2

in the second equation, look to solve for x:

{y = -2 x - 2

{16 x + 6 = -2

subtract 6 from both sides:

{y = -2 x - 2

{16 x = -8

divide both sides by 16:

{y = -2 x - 2

{x = -1/2

substitute x = -1/2 into the first equation:

{y = -1

{x = -1/2

collect results in alphabetical order:

answer:   {x = -1/2 ,   y = -1