To evaluate the combination we proceed as follows:
21C3
Given nCk we shall have:
n!/[(n-k)!k!]
thus plugging the values in the expression we get:
21!/[(21-3)!3!]
=21!/(18!×3!)
=1330
Answer: 1330
Explanation:
We already have phone A 5.3 cm
We just need to find phone B
First we need to find what one-third is as a decimal
Which is 0.3
Now add 0.3 to 5
0.3 + 5 = 5.3
Answer: neither phone a and Phone be 05.3 cm
Rotation about a point does not change any dimensions. C'D' = CD = 2.8 units.
A) First, we need to calculate x. We can do this by doing: 180-(70+50), which is nothing but 60.
Since the largest angle is 60, it means that the side opposite of it is the largest side. Which in this case, side AB.
So the largest side is AB.
Now, let's take a look at the smallest angle which is <B, because AC is the opposite of this angle, it must also be the smallest side.
We're left with angle <50, which is "medium" sized? Obviously, this can just be put in the middle (Side BC)
So, for response A, you should get AC, BC, AB.
Now for problem B, it's the same steps we did above. If you replicate what we did you should get PQ, PR,RQ.
Please let me know how I did.
Happy studying!
Get everything on one side:

. Now we can factor to find the solutions. What we ask ourselves here is "What 2 numbers will add to be +4 and multiply to be -21?" +7 and -3 work because 7-3 = 4 and 7 * -3 = -21. So our factors are (x+7)(x-3). Our solutions, however, are found using the Zero Product Property. If x + 7 = 0, then x = -7. If x - 3 = 0, then x = 3. So our solutions are x = -7 and x = 3.