b)B=2(x^2-3/2.2x+9/4+9/4)=2(x-3/2)^2+9/2>=9/2dấu = xảy ra <=>2(x-3/2)^2=0<=>x=3/2vay.............................
b)
$B=2(x^2-
\frac{3
}{2
}.2x+
\frac{9
}{4
}+
\frac{9
}{4
})=2(x-
\frac{3
}{2
})^2+
\frac{9
}{2
}\g
eq \frac{9
}{2
}$dấu = xảy ra
$\Left
rig
ht
arrow 2(x-
\frac{3
}{2
})^2=0
$$\Left
rig
ht
arrow x=
\frac{3
}{2
}$ Vậy.............................