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
Answer:
-55
Step-by-step explanation:
2nd term=> -1 + -2 × (2 - 1)
3rd term=> -1 + -2 × (3 - 1)
:
28th term=> -1 + -2 × (28 - 1)
=> -1 - 54 = -55
Answer:
Step-by-step explanation:
I think it's a or b
Answer:
the reciprocal of 2/7 is 7/2. you just switch the numbers
The answers are #1 45 #2 24 #3 10