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

b.   40 years.

Step-by-step explanation:

For men  R = 165 - 0.75a

When R = 135:

135 = 165 - 0.75a

0.75a = 165 - 135 = 30

a = 30 / 0.75

=  40 years.

find the magnitude of the trig term  

csc

(

x

)

−

1

by taking the absolute value of the coefficient.

1

find the lower bound of the range.

tap for more

y

=

−

2

find the upper bound of the range.

tap for more

y

=

0

the range is  

y

≤

−

2

or  

y

≥

0

.

(

−

∞

,

−

2

]

∪

[

0

,

∞

)

{

y

|

y

≤

−

2

,

y

≥

0

}

step-by-step explanation:

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step-by-step explanation:

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