Question

giải giúp mình với ạ

 

Answer 1

\(x^2-x>=-\dfrac{1}{4}\)

=>\(x^2-x+\dfrac{1}{4}>=0\)

=>\(\left(x-\dfrac{1}{2}\right)^2>=0\)(luôn đúng)

\(3x^2-2x>-5\)

=>\(3x^2-2x+5>0\)

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

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

=>\(x^2-2\cdot x\cdot\dfrac{1}{3}+\dfrac{1}{9}+\dfrac{14}{9}>0\)

=>\(\left(x-\dfrac{1}{3}\right)^2+\dfrac{14}{9}>0\)(luôn đúng)