A half-life of the isotope is 15 days and at start its mass is 32 g.
A table:
t: m:
0 32 g
15 16 g
30 8 g
45 4 g
60 2 g
75 1 g
In the first column is used an arithmetic sequence ( a 1 = 0, d = 15 ).
In the second column is used a geometric sequence ( a 1 = 32, r = 1/2 )
The slope is 3/1, which can be simplified to 3. Find it by traveling up 3 points and over 1 point form one intersection point to the next.
3 thousands devided by 10= 3 hundreds= (300)
Using the side of the square find the area:
Area = 30^2 = 900 square feet.
The rectangles area is the same, 900 square feet.
Let the width = X
The length would be 2X + 70
Area = length x width
X * 2x+ 70 = 900
This expands to 2x^2 * 70x = 900
Use the quadratic formula to solve for x:
-70 +/- sqrt(70^2-4*2(-900))/2*2
X = 10
Width = x = 10 feet
Length = 2x + 70 = 90 feet
