Question

F(1)=4 e f(3)=-2 sao pontos de uma funçao afim , determine f(7)

Answer 1

F(1) = 4
y = ax + b
4 = a.1 + b
a + b = 4

F(3) = -2
y = ax + b
-2 = a.3 + b
3a + b = -2

$\left \{ {{a + b = 4} \atop {3a + b = -2}} \right. \left \{ {{-a - b = -4} \atop {3a + b = -2}} \right.$
2a = -6
a = -6/2
a = -3

a + b = 4
-3 + b = 4
b = 4 + 3
b = 7

a = -3 e b = 7
y = ax + b
y = -3x + 7

F(x) = -3x + 7
F (7) = -3.(7) + 7
F (7) = -21 + 7
F (7) = -14