Answer: Choice D

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Explanation:
The left portion is the interval (-∞, -2)
This is a shorthand way of saying 
The curved parenthesis says "do not include this endpoint as part of the solution set". Note the open hole at x = -2 in the diagram.
In contrast, the value x = 4 is included (due to the filled in circle), so we use a square bracket for this endpoint. Therefore, the right-hand portion is represented by [4, ∞) which translates to 
Negative and positive infinity will always use a parenthesis, and never a square bracket. This is because we can only approach infinity but never reach it, so we cannot include it as an endpoint.
All of this builds up to the full interval notation to be 
The only square bracket is near the 4; everything else is a curved parenthesis. This is why choice D is the final answer.
It is ten units, as the two sides are of 6 and 8 so you must square them both, add them together (which gives you 100) and then square root that, which gives you 10
1/2+1/3=
3/6+2/6=5/6
The answer is 5/6.
1) 4x+6= 10; x=1
2) c + 5= 15; c=10
3) 2 - a= 18; a= -16
4) -8x=16; x= -2
5) a+6= 12; a=6
6) 3+b= 18; b=6
7) -5 - x= 19; x= -24
8) 7+4b= 34; b= 6.75
Find the powers 
$a^{2}=5+2 \sqrt{6}$
$a^{3}=11 \sqrt{2}+9 \sqrt{3}$
The cubic term gives us a clue, we can use a linear combination to eliminate the root 3 term $a^{3}-9 a=2 \sqrt{2}$ Square $\left(a^{3}-9 a\right)^{2}=8$ which gives one solution. Expand we have $a^{6}-18 a^{4}-81 a^{2}=8$ Hence the polynomial $x^{6}-18 x^{4}-81 x^{2}-8$ will have a as a solution.
Note this is not the simplest solution as $x^{6}-18 x^{4}-81 x^{2}-8=\left(x^{2}-8\right)\left(x^{4}-10 x^{2}+1\right)$
so fits with the other answers.