Medical researchers have determined that for exercise to be beneficial, a person’s desirable heart rate, r, in beats per minute, can be approximated by the formulas
r=143-0.65a for women
r=165-0.75a for men,
where a represents the person’s age. if the desirable heart rate for a man is 135 beats per minute, how old is he?
a.22.5 years old
b.40 years old
c.45 years old
d.42.5 years old
evaluate the function
f(x)=1/2x+3
for f(4).
a. 5
b. 9
c. 11
d. 14