Question

tính

a)x^2-4x+2

b)x^2+x+2

c)x^2-x+3

d)x^2-6x+5

e)x^2-4x+5

Answer 1

a: \(=x^2-4x+4-2=\left(x-2\right)^2-2>=-2\)

Dấu '=' xảy ra khi x=2

b: \(=x^2+x+\dfrac{1}{4}+\dfrac{7}{4}=\left(x+\dfrac{1}{2}\right)^2+\dfrac{7}{4}>=\dfrac{7}{4}\)

Dấu '=' xảy ra khi x=-1/2

c: \(=x^2-x+\dfrac{1}{4}+\dfrac{11}{4}=\left(x-\dfrac{1}{2}\right)^2+\dfrac{11}{4}>=\dfrac{11}{4}\)

Dấu '=' xảy ra khi x=1/2

d: \(=x^2-6x+9-4=\left(x-3\right)^2-4>=-4\)

Dấu '=' xảy ra khi x=3