A half-life is the time taken for the radioactivity of a specified isotope to fall to half its original value. If an isotope had 40g after 2 half-lives the isotope would be reduced to just 10g. 40\cdot\frac{1}{2}\cdot\frac{1}{2}= 1040⋅

2

1



⋅

2

1



=10

Using the function f\left(x\right)=100\cdot\left(\frac {1}{2}\right)^xf(x)=100⋅(

2

1



)

x

where 100 is the original value of the isotope and x is the number of days that have happened.

What is the first day that an isotope with 100g falls below 1g?

d

step-by-step explanation:

answer: the answer is one

step-by-step explanation:

pemdas, in this situation there is no parenthesis or exponents so you go to multiplication, 1x1=1, then division 1/1= 1 then addition 1+1=2 then subtraction 2-1=1

answer: 7 x 2/5 = 2.8 hours, is your answer. your welcome! : 3

step-by-step explanation: first work out how long it took to hose 1/7 of the lawn which is 2/5 hours. times that by 7 to get the whole lawn.

sorry i don't know the other answer. i didn't learn what a proportional relationship is.