Functions are relations that only have one output per input (or graphically passes the vertical line test). You can either go on Desmos and graph this or just look at my explanations below.
1) function, pretty much all polynomials will be a normal function
2) function. This is a rational function, meaning you'll have some weird gaps and lines going to infinity but it's still a function. It's formed by a polynomial divided by another polynomial.
3) function, looks like you can simplify this into a standard rational function.
4) relation, y with an even square root are never going to give you a single solution (due to the nature of a + or - answer; 
= +3 and -3)
A normal vector is the set of coefficients of x, y, and z when the equation is written in standard (or general) form.
Subtracting the left side, we have
... 2(8 -y) -z +5(x -2) = 0
... 16 -2y -z +5x -10 = 0
... 5x -2y -z +6 = 0 . . . . . general form
A normal vector is (5, -2, -1).
The left side is a half circle.
The area of a circle is PI x r^2
The diameter of the circle would be the height of the rectangle, given as 10 feet.
The radius is 1/2 the diameter, so 5 feet.
The area of half the circle is (3.14 x 5^2) / 2 = 39.25 square feet.
The area of the rectangle is 20 x 10 = 200 square feet.
Total area = 200 + 39.25 = 239.25 square feet.
10) x=<span>2<span>y</span></span>
12) x=<span><span><span>14</span>y</span>−1
hope this helps! :)
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