Question

The # N, in millions, of hearing impaired individuals of age X can be approximated by N= 0.00006x^3 + 0.006x^2 - 0.1x +1.4. Approximate to the nearest million the # of hearing impaired individuals of ages 25 and 40. 25= 1.75 and 40= 3 (those are millions!). I know I insert those values but I do NOT understand where I put the parenthesis in the equation!Obviously putting it after the x or before the x makes a BIG difference. HELP!!

Answer 1

N = (6*10^-5)x^3 + (600*10^-5)x^2 -0.1x+1.4.

N = (6*10^-5)(1.75)^3 + (600^10^-5)(1.75)^2 - 0.1x + 1.4,
N = (6*10^-5)5.36 + (600*10^-5)3.06
- 0.175 + 1.4,
N = 35.22*10^-5 + 1836*10^-5 - 0.175 + 1.4,
N = 1871.2 *10^-5 + 1.23,
N = 0.018712 + 1.23 = 1.24 Million.

Part 2: Use same procedure except X = 3.