Question

TÌM GTNN  CỦA

a)    y = 2x² - 3x + 5

b)    y = 2x² - 5x + 7

c)    y = 2x² - 6x + 10

d)    y = \(\frac{x+2}{x^2}\)

e)    y = \(\frac{x}{\left(x-1\right)^2}\)

Answer 1

a)2x² - 3x + 5

\(=2\left(x-\frac{3}{4}\right)^2+\frac{31}{8}\ge\frac{31}{8}\)

Dấu = khi \(x=\frac{3}{4}\)

b)2x² - 5x + 7

\(=2\left(x-\frac{5}{4}\right)^2+\frac{31}{8}\ge\frac{31}{8}\)

Dấu = khi \(x=\frac{5}{4}\)

c) 2x² - 6x + 10

\(=2\left(x-\frac{3}{2}\right)^2+\frac{11}{2}\ge\frac{11}{2}\)

Dấu = khi \(x=\frac{3}{2}\)

c)\(\frac{x+2}{x^2}\ge-\frac{1}{8}\)

Dấu = khi x=-4

d)\(\frac{x}{\left(x-1\right)^2}\ge-\frac{1}{4}\)

Dấu = khi x=-1