Question

1/GTNN 4x^2+4x-1

2/căn(3x^2-4x +3)=1-2x . biết x=trừ căn a . TÌM a?

help. !!!

Answer 1

Bài 1:

\(A=4x^2+4x-1\)

\(=4x^2+4x+1-2\)

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

Dấu "=" xảy ra khi \(x=-\frac{1}{2}\)

Bài 2:

Bình phương 2 vế 

\(\sqrt{\left(3x^2-4x+3\right)^2}=\left(1-2x\right)^2\)

\(\Leftrightarrow3x^2-4x+3=4x^2-4x+1\)

\(\Leftrightarrow2-x^2\Leftrightarrow x^2=2\Leftrightarrow x=-\sqrt{2}\) (tm)

\(x=-\sqrt{a}\Rightarrow-\sqrt{2}=-\sqrt{a}\Rightarrow a=2\)

Answer 2

4x^2+4x-1

=4x^2+4x+1-2

=(2x+1)^2-2

=> (2x+1)^2\(\ge\)0 voi moi x

=> (2x+1)^2 \(\ge\)2

=> GTNN la 2

Answer 3

-2 mà bạn