[tex]0=2t^3-21^2+40t[/tex]
switch sides
[tex]2t^3-21t^2+40t=0[/tex]
solve factoring
[tex]t(t-8)(2t-5)=0[/tex]
using the zero factor principle
[tex]t=0
[/tex]
solve
[tex]t-8=0:t=8[/tex]
solve
[tex]2t-5=0:t= \frac{5}{2} [/tex]
[tex]t=0,t=8,t= \frac{5}{2}[/tex]
Hope this helps
