\(x^2+x+\dfrac{1}{4}=0\)
\((x+\dfrac{1}{2})^2=0\)
\(x+\dfrac{1}{2}=0\)
\(x=-\dfrac{1}{2}\)
\(\text{Vậy }x=-\dfrac{1}{2}\)
\(2x^2+3x+1=0\)
\(2x^2+2x+x+1=0\)
\((2x^2+2x)+(x+1)=0\)
\(2x(x+1)+(x+1)=0\)
\((x+1)(2x+1)=0\)
\(\Rightarrow x+1=0 \text{ hoặc }2x+1=0\)
\(x=-1 \text{ hoặc }2x=-1\)
\(x=-\dfrac{1}{2}\)
\(\text{Vậy }x=-1 \text{ hoặc }x=-\dfrac{1}{2}\)
\(9x^2-16=0\)
\((3x-4)(3x+4)=0\)
\(\Rightarrow 3x-4=0 \text{ hoặc } 3x+4=0\)
\(3x=4\text{ hoặc }3x=-4\)
\(x=\dfrac{4}{3} \text{ hoặc } x=-\dfrac{4}{3}\)
\(\text{Vậy }x=\dfrac{4}{3}\text{ hoặc }x=-\dfrac{4}{3}\)
