Ta có :
\(A\left(-2\right)=B\left(\dfrac{1}{10}\right)\)
\(\Leftrightarrow\left(-2\right)^2-a\left(-2\right)+3=5.\dfrac{1}{10}-1\)
\(\Leftrightarrow4+2a+3=\dfrac{1}{2}-1\)
\(\Leftrightarrow2a+7=-\dfrac{1}{2}\)
\(\Leftrightarrow2a=-7,5\)
\(\Leftrightarrow a=-3,27\)
Vậy ..