Đáp án:
$\displaystyle \begin{array}{{>{\displaystyle}l}} a) \ a=-5;\ b=3\\ b) \ a=-1;\ b=3\\ c) \ a=0;b=-3 \end{array}$
Giải thích các bước giải:
$\displaystyle \begin{array}{{>{\displaystyle}l}} a) \ \{_{B\left(\frac{3}{5} ;0\right) \ \ \in \ h/s}^{A( 0;3) \ \in \ h/s\ } \Leftrightarrow \{_{\frac{3}{5} a+b=0}^{a.0+b=3} \Leftrightarrow \{_{b=3}^{a=-5}\\ Vậy\ a=-5;\ b=3\\ \\ b) \ \{_{B( 2;1) \ \ \in \ h/s}^{A( 1;2) \ \in \ h/s\ } \Leftrightarrow \{_{2a+b=1}^{a+b=2} \Leftrightarrow \{_{b=3}^{a=-1}\\ Vậy\ a=-1;\ b=3\\ \\ c)\{_{B( 21;-3) \ \ \in \ h/s}^{A( 15;-3) \ \in \ h/s\ } \ \Leftrightarrow \{_{21a+b=-3}^{15a+b=-3} \Leftrightarrow \{_{b=-3}^{a=0}\\ Vậy\ a=0;b=-3 \end{array}$
