Question

Mostre que : f(x)=(2x+1).(3x-1)-(3x-2).(2x+1)

Answer 1

 f(x)=(2x+1).(3x-1)-(3x-2).(2x+1)  (2x+1).(3x-1)-(3x-2).(2x+1) = 0 ////////////
 (6x² - 2x + 3x - 1) - (6x² + 3x - 4x - 2) = 0
 6x² + x - 1 - 6x² - 3x + 4x + 2 = 0
2x +1 = 0 ---> 2x = -1 ----> x = - 1/2

 f(x)=(2x+1).(3x-1)-(3x-2).(2x+1)
f(-1/2) = [2(-1/2)+1 . 3(-1/2-1) - [3(-1/2) -2 . 2(-1/2) +1]
f(-1/2) = (-1+1) . (-3/2 -3) - (-3/2-2) . (-1 + 1)
f(-1/2) = 0 - 0
f(-1/2) = 0