f(x) =y
(x² -x +1) y = x² +mx +1
x² y - xy +y - x² - mx -1 =0
( y -1 ) x² - ( y+m) x + y -1 =0
Δ = ( y +m)² - 4 ( y -1 )²
Δ = ( y +m - 2y +2 ) ( y+m + 2y -2)
Δ = ( - y +m +2 ) ( 3y +m -2 ) >0
-y+ m+2 >0 y< m+2
3y +m -2 >0 3y > 2 -m y > ( 2 -m) /3
( 2 - m ) /3 < y < m +2 y= f(x) multimea valorilor functiei
intervalul = I m+2 - ( 2-m)I =4
I2mI =4 2m=4 atunci m=2
2m =-4 atunci m=-2