Answer:
12cm
Step-by-step explanation:
1. Define the variable:
x = length of the rectangle
2x = width of the rectangle
2. Set the equation:
x + 2x is half of the rectangle
2(x + 2x) is the perimeter
So,
2(x + 2x) = 36
2x + 4x = 36
6x = 36
x = 6
Since x is the length, multiply it by 2 to find the width.
2x = 12
First you distribute the 3
(3x-12) (x+5)=0
then you set each equation equal to zero
3x-12=0 & x+5=0
then you solve for x
x =4, -5
So... it has degree of 7, so based on the fundamental theorem of algebra....it can have at most 7 solutions
now.. you have <span>−4, −4i, 2i <--- there are two complex ones there
-4i or 0-4i and 2i or 0+2i
now.. bear in mind that, complex solutions never come all by their lonesome, they come with their sister, the conjugate
thus, that means 0-4i comes with 0+4i and 0+2i comes with 0-2i
that makes only 5 roots though
that simply means that, the -4 one, has a multiplicity of 3
as far as the B) and C) sections, check Descartes Rule of Signs
which surely you've covered already
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