When you have something like this, all you need to do is substitute the values, the last is for what value of x
For the first one;
((x^2+1)+(x-2))(2)
(x^2+x-1)(2)
(2)^2+(2)-1
4+2-1
5
For the second one;
((x^2+1)-(x-2))(3)
(x^2-x+3)(3)
(3)^2-(3)+3
9-3+3
9
For the last one;
3(x^2+1)(7)+2(x-2)(3)
3((7)^2+7)+2((3)-2)
3(49+7)+2(3-2)
3(56)+2(1)
168+2
170
Write the conjugates of them then FOIL both the top and bottom, then factor
So when X is 0, the area of the pool is 1200. That makes A and C impossible... then you can plug in numbers...say the boardwalk is 1 ft wide, add 2 to each dimension and plug in 1 for X. (You're adding 2 because there is a tile on either side of each dimension, including corners).
32x42=1344=4+140+1200
Therefore the answer is B.
If x is rational then x + n is rational
-2n-24=-8(2n-4)
Multiply both sides by -1
2n+24=8(2n-4)
Distribute the right side
2n+24=16n-32
Subtract 2n from both sides
24=14n-32
Add 32 to both sides
56=14n
Divide 14 from both sides
n=4
