Question

Tìm x biết:
a)\(\frac{x-2}{4}=\frac{x+5}{-3}\)
b) \(\frac{x}{3}=\frac{27}{x}\)
Giúp mình với

Answer 1

a)

\(\frac{x-2}{4}=\frac{x+5}{-3}\)

\(\Rightarrow\frac{-3.\left(x-2\right)}{4.\left(-3\right)}=\frac{4.\left(x+5\right)}{4.\left(-3\right)}\)

\(\Rightarrow\frac{-3x+6}{-12}=\frac{4x+20}{-12}\)

\(\Rightarrow-3x+6=4x+20\)

\(\Rightarrow-3x-4x=20-6\)

\(\Rightarrow-7x=14\)

\(\Rightarrow x=-2\)

b)

\(\frac{x}{3}=\frac{27}{x}\)

\(\Rightarrow x.x=3.27\)

\(\Rightarrow x^2=81\)

\(\Rightarrow\orbr{\begin{cases}x=9\\x=-9\end{cases}}\)

T**k mik nhé!