Sagot :
f(-1)= 2x(-1) -12
f(-1)= -2-12
f(-1)= -14
f(x)= 9
Donc 2x-12= 9
x= (9+12):2
x= 21:2
x= 10,5
f(10,5)= 9
f(-1)= -2-12
f(-1)= -14
f(x)= 9
Donc 2x-12= 9
x= (9+12):2
x= 21:2
x= 10,5
f(10,5)= 9
f(-1) = 2*(-1) - 12 = -2-12 = -14
2x -12 = 9
2x = 9+12
2x = 21
x = 21/2
x = 10.5