How do I solve this equation by completing the square. 4X^2 + 12x +5 = 21
1 answer:
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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
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