Method OneYour calculator might be able to do this. Mine does it like this.
6
nCr
2
=
15
Method 2You could simply set up 6C2
This gives you
Method ThreeYou only have to do this a couple of times to see how the cancellation works.
After all the cancellation takes place you have
6*5/2 = 15
What is the equation, it’s hard to understand
Answer: 8x = 72
Step-by-step explanation:
and in case you need to go any further at any point, <em>x = 9</em>
-10 is the answer
Plug in -4 for n so 2x-4-2=-10
Problem 1
Answer: C) No solution
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Explanation:
We have z = -4 and 4z = -4 at the same time. Solving 4z = -4 leads to z = -1
So in effect we have z = -4 and z = -1 at the same time, but this is a contradiction. A variable can only hold one number at a time.
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Problem 2
Answer: C) Infinitely many solutions
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Explanation:
The two equations are equivalent. You can prove as such by isolating 2y in the first equation.
5x = 8-2y
5x+2y = 8
2y = 8-5x
2y = -5x+8
-5x+8 = 2y
This shows the first equation is equivalent to the second, and vice versa. They both graph the same line. Any point along the line is a solution. So that's why there are infinitely many of them.
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Problem 3
Answer: Choice A) 
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Explanation:
The range is the set of the possible y values. We're concerned with every y coordinate of each (x,y) solution. So we only focus on the shaded region.
The dashed line means we exclude the boundary. It's an electric fence we cannot touch. So y > -6 or -6 < y describes part of the range
The other part is 
since y = 3 is the when the highest point occurs.
So writing describes all possible y values of each (x,y) solution in the shaded region.
