Найдите: f(3), f(0), f(-2), если f(x)=21x-7.

\[f(x) = 21x - 7\]

\[f(3) = 21 \cdot 3 - 7 = 63 - 7 = 56.\]

\[f(0) = 21 \cdot 0 - 7 = - 7.\]

\[f( - 2) = 21 \cdot ( - 2) - 7 =\]

\[= - 42 - 7 = - 49.\]