Question

Tìm số nguyên x, biết:

e) (x + 2)/3 = 3/(x + 2)

f) (x - 4)/-5 = -5/(x - 4)

Answer 1

e)

\(\dfrac{x+2}{3}=\dfrac{3}{x+2}\\ =\left(x+2\right)^2=9\\ \left[{}\begin{matrix}x+2=3\\x+2=-3\end{matrix}\right.\\ \left[{}\begin{matrix}x=1\\x=-5\end{matrix}\right.\)

f)

\(\dfrac{x-4}{-5}=\dfrac{-5}{x-4}\\ \left(x-4\right)^2=25\\ \left[{}\begin{matrix}x-4=5\\x-4=-5\end{matrix}\right.\\ \left[{}\begin{matrix}x=9\\x=-1\end{matrix}\right.\)

Answer 2

\(\dfrac{x+2}{3}=\dfrac{3}{x+2}\\ =>\left(x+2\right)^2=9\\ =>\left[{}\begin{matrix}x+2=3\\x+2=-3\end{matrix}\right.=>\left[{}\begin{matrix}x=1\\x=-5\end{matrix}\right.\)

Answer 3

e)

x−4−5=−5x−4(x−4)2=25[x−4=5x−4=−5[x=9x=−1