contestada

the equation R= -0.028(T) + 20.8 can be used to predict the world record in the 200-m dash, where R is the record in seconds and T is the number of years since 1920. in what year will the record be 18.0 second?

Respuesta :

[tex] \bf R=-0.028(t)+20.8~~
\begin{cases}
R=seconds\\
t=\stackrel{1920+}{years}\\
------\\
R=18.0
\end{cases}\implies 18=-0.028t+20.8
\\\\\\
0.028t=20.8-18\implies 0.028t=2.8\implies t=\cfrac{2.8}{0.028}\implies t=100
\\\\\\
\stackrel{\textit{since \underline{t} is years since 1920}}{1920+100\implies 2020} [/tex]

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