Answer:
The man would be 40 years old.
Step-by-step explanation:
Blood pressure as function of age:
Is given by the following equation:
[tex]P = 0.006A^2 - 0.02A + 120[/tex]
Find the age of a man whose normal blood pressure measures 129 mmHg.
This is A for which P = 129. So
[tex]129 = 0.006A^2 - 0.02A + 120[/tex]
[tex]0.006A^2 - 0.02A - 9 = 0[/tex]
Solving a quadratic equation:
Given a second order polynomial expressed by the following equation:
[tex]ax^{2} + bx + c, a\neq0[/tex].
This polynomial has roots [tex]x_{1}, x_{2}[/tex] such that [tex]ax^{2} + bx + c = a(x - x_{1})*(x - x_{2})[/tex], given by the following formulas:
[tex]x_{1} = \frac{-b + \sqrt{\Delta}}{2*a}[/tex]
[tex]x_{2} = \frac{-b - \sqrt{\Delta}}{2*a}[/tex]
[tex]\Delta = b^{2} - 4ac[/tex]
In this question:
Quadratic equation with [tex]a = 0.006, b = -0.02, C = -9[/tex]. So
[tex]\Delta = (-0.02)^2 - 4(0.006)(-9) = 0.2164[/tex]
[tex]A_{1} = \frac{-(-0.02) + \sqrt{0.2164}}{2*(0.006)} = 40.4[/tex]
[tex]A_{2} = \frac{-(-0.02) - \sqrt{0.2164}}{2*(0.006)} = -37.1[/tex]
Age has to be a positive number, so rounding to the nearest year:
The man would be 40 years old.
