A= 3x2 - 12x+10
=3x2-12x+12-2
=3(x2-4x+4)-2
=3(x-2)2-2
do3(x-2)2\(\ge0\forall x\)
=> 3(x-2)2-2\(\ge-2\)
=> A\(\ge-2\)
Min A=-2khi
x-2=0
=> x=2
A= 3x2 - 12x+10
= 3x2-12x+12-2
= 3(x2-4x+4)-2
=3(x-2)2-2
do 3(x-2)2\(\ge0\forall x\)
=> 3(x-2)2-2\(\ge-2\)
=> A\(\ge-2\)
Min A =-2 khi
x-2=0
=> x=2