Question

Tìm x, biết:

a) x^2-5x=0

b) x^2-x=0 

c)36x^2-49=0

Answer 1

\(a,x^2-5x=0\)

\(x.\left(x-5\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x=0\\x-5=0\Rightarrow x=5\end{cases}}\)

vậy x=0 hay x=5

\(b,x^2-x=0\)

\(x.\left(x-1\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x=0\\x-1=0\Rightarrow x=1\end{cases}}\)

vậy x=0 hay x=1

\(c,36x^2-49=0\)

\(\Rightarrow36x^2=49\)

\(x^2=\frac{49}{36}=\frac{7^2}{6^2}=\frac{\left(-7\right)^2}{\left(-6\right)^2}\)

\(\Rightarrow\orbr{\begin{cases}x=\frac{7}{6}\\x=-\frac{7}{6}\end{cases}}\)

vậy x=\(\frac{7}{6}hayx=-\frac{7}{6}\)