Dada a função f(x)=|x| -2x, calcular f(-1),f(1/2) e f(-2/3).

F(-1) = |-1| - 2 * (-1) = 3

F(1/2) = |1/2| - 2 * (1/2) = 1/2 - 1 = -1/2

F(-2/3) = |-2/3| - 2 * (-2/3) = 2/3 + 4/3 = 2

e

F(|a|)= ||a||-2|a|

se a<=0

F(|a|)= |-a|-2|a|=|a|-2|a|=-|a|

se a>0

F(|a|)= |a|-2|a|=-|a|

logo F(|a|)=-|a|

 

F(-1) = -1-2x => x = 1/2

F(1/2)= 1/2-2x => x= -1/4

F(-2/3)= -2/3-2x => x= 1/3