Question

Solve the following by using the method of completing square.
$3y^2-7y-20=0$

Answer 1

According to question,

$\begin{array}{c}\Rightarrow 3\left[y^2-\frac{7}{3}y+\frac{49}{36}-\frac{49}{36}\right]-20=0\\ \Rightarrow 3{\left(y-\frac{7}{6}\right)}^2-\frac{49}{12}-20=0\\ =20+\frac{49}{12}\\ \Rightarrow {\left(y-\frac{7}{6}\right)}^2=\frac{289}{36}\\ hence,weget\\ \Rightarrow y=\frac{-10}{6}=\frac{-5}{3}\\ \Rightarrow y=\frac{24}{6}=4\end{array}$