Chapter 3 - Applied Project - Where Should a Pilot Start Descent? - Page 208: 4

$P(x)=-0.0000494066006 x^3+0.004780241572 x^2$ See image

$P(x)=\frac{-2h}{l^3}x^3+\frac{3h}{l^2}x^2$ $h=6.629mi$ $l=64.5mi$ $P(x)=\frac{-2\times6.629mi}{(64.5mi)^3}x^3+\frac{3\times6.629mi}{(64.5mi)^2}x^2$ $P(x)=-0.0000494066006 x^3+0.004780241572 x^2$