Question

làm giúp vs nha

B1 tìm GTNN

a, A= x² - 20x +101

b, B= 4x² + 4x + 2

c, C= x²- 4xy + 5y² + 10x -22y + 28

B2 tìm GTLN

a, x - x²

b, 4x - x² + 3

Answer 1

Bài 1:

a) \(A=x^2-20x+101\)

\(=x^2-2\cdot x\cdot10+10^2-100+101\)

\(=\left(x-10\right)^2+1\ge1\)

Dấu "=" xảy ra khi \(x=10\)

Vậy \(MIN_A=1\) khi \(x=10\)

b) \(B=4x^2+4x+2\)

\(=\left(2x^2\right)^2+2\cdot x\cdot2+2^2-4+2\)

\(=\left(2x+2\right)^2-2\ge-2\)

Dấu "=" xảy ra khi \(x=-1\)

Vậy \(MIN_B=-2\) khi \(x=-1\)

c) tự làm :)))