Marie is logging the number of radioactive isotopes she observes every minute. She has determined her function to be f(x) = −4x + 120. Based on the situation above, describe any necessary restrictions to the domain and range. Provide justification for the restrictions.

Question

Marie is logging the number of radioactive isotopes she observes every minute. She has determined her function to be f(x) = −4x + 120.  Based on the situation above, describe any necessary restrictions to the domain and range. Provide justification for the restrictions.

campbell_st · Answer

well x will only be positive....

campbell_st · Answer

times can't be negative.... and its a 1st quadrant graph... the upper value for x is when f(x) is 0. if the graph goes below the x - axis... you're saying the radioactivity is a negative value. 

so just find the intercepts of the graph... the domain of x will be from 

x = 0 to   x-intercept.