Question

tìm x biết 5x(x-3)+4x-12=0

Answer 1

Ta có: 5x(x-3)+4x-12=0

=> 5x(x-3)+4(x-3)=0

=> (5x+4).(x-3)=0

\(\Rightarrow\orbr{\begin{cases}5x+4=0\Rightarrow5x=-4\Rightarrow x=-\frac{4}{5}\\x-3=0\Rightarrow x=3\end{cases}.}\)

Vậy x=3; -4/5

Answer 2

5x(x-3)+4(x-3)=0

(x-3)(5x+4)=0

=>\(\hept{\begin{cases}x-3=0\\5x+4=0\end{cases}}\)=>\(\hept{\begin{cases}x=3\\x=-\frac{4}{5}\end{cases}}\)