C1 :
$\frac{3}{8}$ : $\frac{-3}{5}$
= $\frac{3}{8}$ . $\frac{-5}{3}$
= $\frac{-5}{8}$
C2 :
b) x : $\frac{1}{5}$ + $\frac{1}{8}$ = $\frac{3}{4}$
⇔ x : $\frac{1}{5}$ = $\frac{3}{4}$ - $\frac{1}{8}$
⇔ x : $\frac{1}{5}$ = $\frac{5}{8}$
⇔ x = $\frac{5}{8}$ . $\frac{1}{5}$
⇔ x = $\frac{1}{8}$
c) -0,52 : x = -9,36 : 16,38
⇔ -0,52 : x = $\frac{-4}{7}$
⇔ x = -0,52 : $\frac{-4}{7}$
⇔ x = $\frac{91}{100}$
d) $(2x-1)^{4}$ = 81
⇔ $(2x-1)^{4}$ = $±3^{4}$
⇔ \(\left[ \begin{array}{l}2x-1=3\\2x-1=-3\end{array} \right.\)
⇔ \(\left[ \begin{array}{l}2x=4\\2x=-2\end{array} \right.\)
⇔ \(\left[ \begin{array}{l}x=2\\x=-1\end{array} \right.\)
~CHÚC BẠN HỌC TỐT~
