A person's systolic blood pressure,

Question

which is measured in millimeters of mercury (mm Hg), depends on a person's age, in years. The equation: P = 0.004 y 2 − 0.02 y + 118 gives a person's blood pressure, P , at age y years

B.) If a person's systolic pressure is 123.6 mm Hg, what is their age (rounded to the nearest whole year)?

Answer 1

It is just solving a quadratic equation:

.004y^2 - .02y + 118 = 123.6 or

.004 y^2- .02 y - 5.6 = 0 Multiply both sides by 1000 and then divide by 4:

4y^2 -20y -5600=0

y^2 - 5y - 1400 = 0 Now solve it using quadratic Formula or factoring:

( y - 40)( y + 35) = 0

y = -35 which is not acceptable since the age cannot be negative. or:

y = 40 which is the answer.

You can solve the quadratic equation by the Quadratic Formula and get the same answer.

Answer 2

Need to rewrite the formula; ^ is power.