tính bằng hai cách :
3/22 x 3/11 x 22 (1/2 + 1/3 ) x 2/5 3/5 x 17/21 + 17/21 x 2/5
GIÚP MK VS NHA
tính bằng hai cách : 3/22 x 3/11 x 22 (1/2 + 1/3 ) x 2/5 3/5 x 17/21 + 17/21 x 2/5
By Sarah
a, Cách 1: `3/22 xx 3/11 xx 22 = (3 xx 3 xx 22)/(22 xx 11 xx 1) = (9 xx 22)/(22 xx 11) = 9/11`
Cách 2: `3/22 xx 3/11 xx 22 = 3/22 xx (3/11 xx 22) = 3/22 xx 6 = 18/22 = 9/11`
b, Cách 1: `(1/2 + 1/3) xx 2/5 = (3/6 + 2/6) xx 2/5 = 5/6 xx 2/5 = 2/6 = 1/3`
Cách 2: `(1/2 + 1/3) xx 2/5 = 1/2 xx 2/5 + 1/3 xx 2/5 = 1/5 + 2/15 = 3/15 + 2/15 = 5/15 = 1/3`
c, Cách 1: `3/5 xx 17/21 + 17/21 xx 2/5 = 51/105 + 34/105 = 85/105 = 17/21`
Cách 2: `3/5 xx 17/21 + 17/21 xx 2/5 = 17/21 xx (3/5 + 2/5) = 17/21 xx 1 = 17/21`
Đáp án:
Giải thích các bước giải:
$\text{1) $\frac{3}{22}$ x $\frac{3}{11}$ x 22}$
$\text{= $\frac{9}{249}$ x 22}$
$\text{= $\frac{9}{11}$}$
$\text{2) ($\frac{1}{2}$ + $\frac{1}{3}$) x $\frac{2}{5}$}$
$\text{= $\frac{5}{6}$ x $\frac{2}{5}$}$
$\text{= $\frac{1}{3}$}$
$\text{3)$\frac{3}{5}$ x $\frac{17}{21}$ x $\frac{17}{21}$ x $\frac{2}{5}$}$
$\text{=$\frac{17}{21}$ x ($\frac{2}{5}$+ $\frac{3}{5}$)}$
$\text{=$\frac{17}{21}$ x 1}$
$\text{=$\frac{17}{21}$}$