Câu 4: Trang 24 toán VNEN 7 tập 1
Tìm x, biết: a) x : $(\frac{3}{4})^{3}$ = $(\frac{3}{4})^{2}$; b) $(\frac{2}{5})^{5}$ . x = $(\frac{2}{5})^{8}$.
Bài Làm:
a) x : $(\frac{3}{4})^{3}$ = $(\frac{3}{4})^{2}$ $\Rightarrow$ x = $(\frac{3}{4})^{2}$ . $(\frac{3}{4})^{3}$ $\Rightarrow$ x = $(\frac{3}{4})^{5}$ $\Rightarrow$ x = $\frac{243}{1024}$;
b) $(\frac{2}{5})^{5}$ . x = $(\frac{2}{5})^{8}$ $\Rightarrow$ x = $(\frac{2}{5})^{8}$ : $(\frac{2}{5})^{5}$ $\Rightarrow$ x = $(\frac{2}{5})^{3}$ $\Rightarrow$ x = $\frac{8}{125}$.