(2x-1).(4y+2)=-30 Tìm a,b€z biết a.b=18 và a+b =11

$a) (2x-1).(4y+2)=-30$

Ta có:

1) \(\left[ \begin{array}{l}2x-1=1\\4y+2=-30\end{array} \right.\) 

\(⇔\left[ \begin{array}{l}x=1\\y=-8\end{array} \right.\)

2) \(\left[ \begin{array}{l}2x-1=2\\4y+2=-15\end{array} \right.\) \(⇔\left[ \begin{array}{l}x=\dfrac{3}{2}\\y=\dfrac{-13}{4}\end{array}(vl) \right.\) 

3) \(\left[ \begin{array}{l}2x-1=3\\4y+2=-10\end{array} \right.\) \(⇔\left[ \begin{array}{l}x=2\\y=-3\end{array} \right.\) 

b) Ta có: $\begin{cases}ab=18\\a+b=11\end{cases}$

$⇔ \begin{cases}a=9\\b=2\end{cases}$