I suspect the width is 7x^2 (please double-check).
If that's the case,
the length of the pool is
L=(7x^3-42x^2)/(7x^2)
=7x^3/(7x^2)-42x^2/(7x^2)
=x-6
Im probably wrong but i think you would do -4 - 7 + 3 = -8
First, solve 10x + y = -20 for y: y = -20 - 10x
Next, substitute -20 -10x for y in the second equation:
-20 - 10x = 2x^2 - 4x - 16.
Rearranging, 2x^2 + 6x + 4 = 0
Simplifying, x^2 + 3x + 2 = 0
The roots of this poly eqn are -1 and -2. Therefore, x = -1 and x = -2.
One by one, subst. these x-values into y = -20 - 10x to find the corresponding y-values.
Your answers should look like this: (-1, y) and (-2, y) (different values for y).
The imaginary number,
<em /><em>
i, </em>is <em />equal to:
![\sqrt{-1}](https://tex.z-dn.net/?f=%20%5Csqrt%7B-1%7D%20)
Thus we can simplify √-17 into:
![\sqrt{-1*17}](https://tex.z-dn.net/?f=%20%5Csqrt%7B-1%2A17%7D%20)
Thus the square root of -17 becomes:
![\sqrt{17} i](https://tex.z-dn.net/?f=%20%5Csqrt%7B17%7D%20i)
.
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