Question

tìm GTNN

a, 2x²-x+1

b,x(3x-1)

c,x²+2y²-2xy+2x+y+1

khi chiều em sửa trog câu kia nhx sao nó ko hiện ra ạ

 

Answer 1

a: \(=2\left(x^2-\dfrac{1}{2}x+\dfrac{1}{2}\right)\)

\(=2\left(x^2-2\cdot x\cdot\dfrac{1}{4}+\dfrac{1}{16}+\dfrac{7}{16}\right)\)

\(=2\left(x-\dfrac{1}{4}\right)^2+\dfrac{7}{8}>=\dfrac{7}{8}\)

Dấu '=' xảy ra khi x=1/4

b: \(=3x^2-x\)

\(=3\left(x^2-\dfrac{1}{3}x\right)\)

\(=3\left(x^2-2\cdot x\cdot\dfrac{1}{6}+\dfrac{1}{36}-\dfrac{1}{36}\right)\)

\(=3\left(x-\dfrac{1}{6}\right)^2-\dfrac{1}{12}>=-12\)

Dấu '=' xảy ra khi x=1/6

Answer 2

=3(x2−2⋅x⋅16...