Chapter 9 - Solving Quadratic Equations - 9.3 - Solving Quadratic Equations Using Square Roots - Exercises - Page 501: 32

$w\approx 38.7$ in $l\approx 77.4~$in

$$l=2w$$ $$V=lwh$$ $$72~000=2w(w)24$$ $$72~000=48w^2$$ $$w^2=1500$$ $$w=\pm\sqrt{1500}\approx \pm38.7\text{ in.}$$ Take the positive value: $w\approx 38.7$ in. Then $l=2w\approx 77.4$ in.