3) 18v2−15v−18
=3(6v2−5v−6)
=3(2v−3)(3v+2)
Answer: 
Step-by-step explanation:
You should get this answer because the simpliest form of a radical is that you shouldn't have any radical in the denominator. In order to get rid of the radical sign in the denominator, you have to multiply the numerator and the denominator with the
.
Look at the image below for further explanation
I think it’s either b or c
Initial amount,
.
Final amount,
.
Time taken, t = 6:00 - 2:00 = 4 hour.
We know,

Therefore, the half-life of the isotope is 1.024 hours.
Hence, this is the required solution.