Suppose we want to choose 2 letters, without replacement, from the 4 letters A, B, C, and D. (a) How many ways can this be done, if the order of the choices matters?

(b) How many ways can this be done, if the order of the choices does not matter?

Letters can be chosen in 12 different ways, if order matters, or 6 different ways, if order doesn't matter.

Step-by-step explanation:

Since we want to choose 2 letters, without replacement, from the 4 letters A, B, C, and D, to determine in how many ways can this be done, if the order of the choices matters, and in how many ways can this be done, if the order of the choices does not matter, the following calculations must be performed:

If order matters =

(4 x 3 x 2 x 1) / 2 = X

24/2 = X

12 = X

If the order doesn't matter =

12/2 = X

6 = X

Therefore, letters can be chosen in 12 different ways, if order matters, or 6 different ways, if order doesn't matter.

99

step-by-step explanation:

-3

step-by-step explanation:

a drawing really does here:

so i draw the horizontal line y=2 and the vertical line x=-2 at this intersection i put b (this is where my right angle is going to be).   so point b is at (-2,2).   point a is 5 units long and is also on y=2 so this point has to be (3,2) or (-7,2) -doesn't matter i will go with (3,2).

now we know c is at (-2,y) we don't know the y yet bet we know that c is on x=-2.

we have the area of the triangle is .5bh=12.5

we know the base length is 5 (ab)

we have the height is (2-y) if you look at your

plug in

.5(5)(2-y)=12.5

solve for y to get the y-coordinate for c

2.5(2-y)=12.5

divide both sides by 2.5 giving:

2-y=5

now subtract 2 on both sides

-y=3

y=-3