[tex]Formula~dependentei~rezistentei~de~temperatura:\\ \\ \\
R=R_{0}\times (1+\alpha \times \Delta t)\\ \\ \\
De~unde~scoatem~\alpha:\\ \\
1+\alpha \times \Delta t=\frac R{R_{0}}\\ \\
\alpha \times (t_{1}-t_{0})=\frac R{R_{0}}-1\\ \\
\alpha=\frac{R-R_{0}}{R_{0}\times (t_{1}-t_{0})}\\ \\ \\
Inlocuim~datele~din~grafic:\\ \\
\alpha=\frac{60-20}{20\times (500-0)}=0,004=4\times 10^{-3}\\ \\ \\
Deci,~raspunsul~este~c).[/tex]
