Respostas

2014-02-14T22:42:45-02:00
f(1) = 1 = (1,1)
y = ax + b
1 = a + b
a + b = 1

f(3)=11 = (3,11)
y = ax + b
11 = 3a + b
\begin{cases} & \text{ } a + b = 1 \to a = 1 - b \\ 
& \text{ }3a + b = 11 \end{cases}
\\\\\\
3(1 - b) + b = 11\\\\
3 - 3b + b = 11\\\\
-2b = 11 - 3\\\\
b = - \frac{8}{2}\\\\
\boxed{b = -4}\\\\
a = 1 - b\\\\
a = 1 - (-4)\\\\
\boxed{a = 5}\\\\
\boxed{\boxed{y = 5x - 4}}