\(\displaystyle{5}{x}^{{2}}+{12}{x}-{20}=-{3}{x}\)

Calculation

\(\displaystyle{5}{x}^{{2}}+{12}{x}-{20}=-{3}{x}\)

\(\displaystyle{5}{x}^{{2}}+{15}{x}-{20}={0}\)

\(\displaystyle{x}^{{2}}+{3}{x}-{4}={0}\)

\(\displaystyle{x}^{{2}}+{4}{x}-{x}-{4}={0}\)

\(\displaystyle{x}{\left({x}+{4}\right)}-{1}{\left({x}+{4}\right)}={0}\)

\(\displaystyle{\left({x}+{4}\right)}{\left({x}-{1}\right)}={0}\)

\(x=-4\ \&\ x=1\)