Question

a, Tìm GTNN E= x^2-5x-2

Answer 1

 `E= x^2-5x-2`

`E=  x^2 -5x + 25/4 -33/4`

`E= (x-5 /2)^2 -33/4`

`E=  (x-5 /2)^2 -33/4 >= -33/4`

dấu ''`=`'' xảy ra khi `x- 5/2 = 0 <=>x=5/2`

vậy Min`E=-33/4 <=>x=5/2`

Answer 2

\(=x^2-2\cdot x\cdot\dfrac{5}{2}+\dfrac{25}{4}-\dfrac{33}{4}=\left(x-\dfrac{5}{2}\right)^2-\dfrac{33}{4}>=-\dfrac{33}{4}\)

Dấu '=' xảy ra khi x=5/2