Answer:
Step-by-step explanation:
let x,y be the sides of court.
2(x+y)=90
x+y=90/2=45
y=45-x
xy=500
x(45-x)=500
45x-x²=500
x²-45x+500=0
x²-25x-20x+500=0
x(x-25)-20(x-25)=0
(x-25)(x-20)=0
x=25,20
when x=25
y=45-x=45-25=20
when x=20
y=45-20=25
sides are 25 ft,20 ft.
Staals half
1 gram left
0.3 grams left
half lives are normally written in years
it goes likt this

A=final amount
P=initila amount
t=time elapsed
h=time half life is (same units as time)
let's use days as the units of time
we are given
initial amount=1gram
final amount=0.3gram
time=4 days
so

solve for h

take the ln of both sides


times both sides by h

divide both sides by ln(0.3)

use calculator
h=2.30287
3 sig figs
h=2.303 days
I did some math and i got this
x = -2