=>F(-2)=m.(-2)2+2.(-2)+16=0
=>4m-4+16=0
=>4m=-12
=>m=-3
Suy ra f(-2) = m . ( -2 )^2 + 2 . ( -2 ) + 16 = 0
Suy ra 4m - 4 + 16 = 0
4m - 4 = -16
4m = -16 + 4 = -12
m = -12 : 4 = -3
Vậy m = -3
F=(-2)=m.(-2)^2+2.(-2)+16=0
=>4m-4+16=0
=>4m+12=0
=>4m=-12
=>m=-3
Ta thay -2 vào f(x) ta có :
f(-2) = m(-2)2+2(-2)+16=m4-4+16=0
<=>4(m-1+4)=0
<=>m+3=0<=>m=-3