Answer:
The third one is correct
Step-by-step explanation:
Answer:

Step-by-step explanation:
we are given half-life of PO-210 and the initial mass
we want to figure out the remaining mass <u>after</u><u> </u><u>4</u><u>2</u><u>0</u><u> </u><u>days</u><u> </u>
in order to solve so we can consider the half-life formula given by

where:
- f(t) is the remaining quantity of a substance after time t has elapsed.
- a is the initial quantity of this substance.
- T is the half-life
since it halves every 140 days our T is 140 and t is 420. as the initial mass of the sample is 5 our a is 5
thus substitute:

reduce fraction:

By using calculator we acquire:

hence, the remaining sample after 420 days is 0.625 kg
2/11 is 0.181818 as a decimal so closest to 0.
I can’t understand the question can you write it more clearly?
<em><u>The solution is (4, 4)</u></em>
<em><u>Solution:</u></em>
<em><u>Given system of equations are:</u></em>

<em><u>Substitute eqn 2 in eqn 1</u></em>

Make the right side of equation 0

<em><u>Solve by quadratic equation</u></em>

<em><u>Substitute x = 4 in eqn 2</u></em>
y = 2(4) - 4
y = 8 - 4
y = 4
Thus solution is (4, 4)