Solve for c :
x⁴ + cx² + 100 = 0
cx² = -(x⁴ + 100)
c = - (x⁴ + 100)/x²
If x = 0, the right side is undefined and c would have no solution.
Set up and solve an equation of ratios. Comparing shadow lengths, we get 100/6; comparing heights, we get x/8. Set these two ratios equal to one another and solve the resulting equation for x:
100 x
----- = ------ Then 6x=800, and x = 800 feet^2 over 6 feet. Your answer
6 8
must have the unit of measurement "ft."
There's a site called m.a.t.h.w.a.y, and you can type in those functions in order to get the graph ;)
60% decrease.
$105-$42 = $63
$63/$105 = 0.6
0.6 x 100 = 60