a) Obliczmy brakujące współczynniki prostej m:

$\{\begin{array}{l}A\cdot 14-5\cdot \left(-2\right)=0\\ A\cdot 7-2\cdot 0+C=0\end{array}$  

$\{\begin{array}{l}14A+10=0\\ 7A+C=0\end{array}$  

$\{\begin{array}{l}14A=-10\\ 7A+C=0\end{array}$

$\{\begin{array}{l}A=-\frac{10}{14}\\ 7A+C=0\end{array}$

$\{\begin{array}{l}A=-\frac{5}{7}\\ 7\cdot \left(-\frac{5}{7}\right)+C=0\end{array}$

$\{\begin{array}{l}A=-\frac{5}{7}\\ -5+C=0\end{array}$

$\{\begin{array}{l}A=-\frac{5}{7}\\ C=5\end{array}$

---

b) Obliczmy brakujące współczynniki prostej m:

$\{\begin{array}{l}1\cdot 4-B\cdot \left(-3\right)=0\\ 1+B\cdot \left(-3\right)+C=0\end{array}$  

$\{\begin{array}{l}4+3B=0\\ 1+\left(-3B\right)+C=0\end{array}$  

$\{\begin{array}{l}3B=-4\\ C=3B-1\end{array}$

$\{\begin{array}{l}B=-\frac{4}{3}\\ C=3\cdot \left(-\frac{4}{3}\right)-1\end{array}$

$\{\begin{array}{l}B=-\frac{4}{3}\\ C=-4-1\end{array}$

$\{\begin{array}{l}B=-1\frac{1}{3}\\ C=-5\end{array}$

---

c) Obliczmy brakujące współczynniki prostej m:

$\{\begin{array}{l}3\cdot \left(-20\right)+B\cdot 15=0\\ 3\cdot 0+B\cdot 0+C=0\end{array}$  

$\{\begin{array}{l}-60+15B=0\\ C=0\end{array}$  

$\{\begin{array}{l}15B=60\\ C=0\end{array}$

$\{\begin{array}{l}B=4\\ C=0\end{array}$

---

d) Obliczmy brakujące współczynniki prostej m:

$\{\begin{array}{l}A\cdot 2+1\cdot 4=0\\ A\cdot \frac{1}{2}+7+C=0\end{array}$  

$\{\begin{array}{l}2A+4=0\\ \frac{1}{2}A+7+C=0\end{array}$  

$\{\begin{array}{l}2A=-4\\ \frac{1}{2}A+7+C=0\end{array}$

$\{\begin{array}{l}A=-2\\ \frac{1}{2}\cdot \left(-2\right)+7+C=0\end{array}$

$\{\begin{array}{l}A=-2\\ -1+7+C=0\end{array}$

$\{\begin{array}{l}A=-2\\ 6+C=0\end{array}$

$\{\begin{array}{l}A=-2\\ C=-6\end{array}$