duongbaongoc0915886
Bài 1: Tính
$\alpha$)$\frac{4}{5}$.$\frac{20}{41}$+$\frac{34}{4}$ $\frac{30}{41}$
=$\frac{16}{41}$+$\frac{255}{41}$
=$\frac{274}{41}$
$b$)$\frac{4}{5}$. $\frac{35}{5}$- $\frac{3}{7}$.$35$
$=$$\frac{28}{5}$$-$$15$
$=$$\frac{-47}{5}$
Bài 2: Tính
$1$)$\frac{3.4.5.6}{10.2.6.12}$
$=$$\frac{3.2.2.5.6}{2.5.2.3.2.6.2}$
$=$$\frac{1}{4}$
$2$) $\frac{11.13.15.17}{17.5.3.17}$
$=$$\frac{11.13}{17}$
$=$$\frac{143}{17}$
Bài 3: Tìm $x$
$a$)$\frac{4}{7}$$+$$\frac{3}{6}$$x$$=$$\frac{8}{9}$
$\frac{3}{6}$.$x$$ =$$\frac{20}{63}$
$x$ = $\frac{20}{63}$: $\frac{3}{6}$
$x$ = $\frac{40}{63}$
Vậy $x$$=$ $\frac{40}{63}$
$b$)$\frac{9}{5}$. $\frac{9}{x}$$=$ $\frac{27}{35}$
$\frac{9}{x}$$=$$\frac{27}{35}$: $\frac{9}{5}$
$\frac{9}{x}$$=$$\frac{3}{7}$
$9$:$x$$=$$\frac{3}{7}$
$x$$=$$\frac{3}{7}$.$9$
$x$$=$$\frac{27}{7}$
Vậy $x$$=$$\frac{27}{7}$
Học tốt.
