Question

Giúp me từ câu 3 đến câu 9 nhé

Answer 1

3: \(=4x^2+4x+1+2=\left(2x+1\right)^2+2>0\)

4: \(=9x^2-6x+1+4=\left(3x-1\right)^2+4>0\)

5: \(=4\left(x^2+\dfrac{3}{2}x+\dfrac{3}{4}\right)\)

\(=4\left(x^2+2\cdot x\cdot\dfrac{3}{4}+\dfrac{9}{16}+\dfrac{3}{16}\right)\)

\(=4\left(x+\dfrac{3}{4}\right)^2+\dfrac{3}{4}>0\)

6: \(=4\left(x^2-\dfrac{5}{2}x+\dfrac{7}{4}\right)\)

\(=4\left(x^2-2\cdot x\cdot\dfrac{5}{4}+\dfrac{25}{16}+\dfrac{3}{16}\right)\)

\(=4\left(x-\dfrac{5}{4}\right)^2+\dfrac{3}{4}>0\)