Hopes this helps:
Answer: x = -2, -2/3
If it wrong I am sorry
Answer:
Given that,
The number of grams A of a certain radioactive substance present at time, in years
from the present, t is given by the formula

a) To find the initial amount of this substance
At t=0, we get


We know that e^0=1 ( anything to the power zero is 1)
we get,

The initial amount of the substance is 45 grams
b)To find thehalf-life of this substance
To find t when the substance becames half the amount.
A=45/2
Substitute this we get,


Taking natural logarithm on both sides we get,







Half-life of this substance is 154.02
c) To find the amount of substance will be present around in 2500 years
Put t=2500
we get,




The amount of substance will be present around in 2500 years is 0.000585 grams
Step-by-step explanation:
4/5 gallons for 280 ft² (the ² is missing in the question ...).
3 gallons would be 15/5.
so, what do I need to multiply 4 with to get 15 ?
4×x = 15
x = 15/4
multiplying now also 280 ft² with this factor gives us the answer :
280 × 15/4 = 70 × 15 = 1050 ft²
they can paint 1050 ft² with 3 gallons of paint.
You eliminate or ‘take away’ the answers that you know or think that r wrong. The last answer that’s left is your answer.