a) A= -$\frac{5}{7}$ . $\frac{2}{11}$ + $\frac{-5}{7}$ . $\frac{9}{11}$ + 1$\frac{5}{7}$
b) B= 50% . 1$\frac{1}{3}$ . 20 . $\frac{7}{35}$ . 0,75
dấu “.” là nhân nha các bạn
a) A= -$\frac{5}{7}$ . $\frac{2}{11}$ + $\frac{-5}{7}$ . $\frac{9}{11}$ + 1$\frac{5}{7}$
b) B= 50% . 1$\frac{1}{3}$ . 20 . $\frac{7}{35}$ . 0,75
dấu “.” là nhân nha các bạn
Giải:
a) A = $\frac{-5}{7}$ . $\frac{2}{11}$ + $\frac{-5}{7}$ . $\frac{9}{11}$ + 1$\frac{5}{7}$
A = $\frac{-5}{7}$ . ( $\frac{2}{11}$ + $\frac{9}{11}$) + $\frac{12}{7}$
A = $\frac{-5}{7}$ . $\frac{11}{11}$ + $\frac{12}{7}$
A = $\frac{-5}{7}$ . 1 + $\frac{12}{7}$
A = $\frac{-5}{7}$ + $\frac{12}{7}$
A = $\frac{-5+12}{7}$ = $\frac{7}{7}$ = 1
b) B = 50% . 1$\frac{1}{3}$ . 20 . $\frac{7}{35}$ . 0,75
B = $\frac{50}{100}$ . $\frac{4}{3}$ . 20 . $\frac{1}{5}$ . $\frac{75}{100}$
B = $\frac{1}{2}$ . $\frac{4}{3}$ . 20 . $\frac{1}{5}$ . $\frac{3}{4}$
B = ( $\frac{1}{2}$ . 20) . ($\frac{4}{3}$ . $\frac{3}{4}$) . $\frac{1}{5}$
B = 10 . 1 . $\frac{1}{5}$ = 2
Đáp án: A = 1 B = 2
Đáp án+Giải thích các bước giải:
$a) A=-\dfrac{5}{7}.\dfrac{2}{11}+\dfrac{-5}{7}.\dfrac{9}{11}+1\dfrac{5}{7}\\=\dfrac{-5}{7}.\left(\dfrac{2}{11}+\dfrac{9}{11}\right)+\dfrac{12}{7}\\=\dfrac{-5}{7}.1+\dfrac{12}{7}\\=\dfrac{-5}{7}+\dfrac{12}{7}\\=\dfrac{7}{7}\\=1$
$b)B=50\%.1\dfrac{1}{3}.20.\dfrac{7}{35}.0,75\\=\dfrac{1}{2}.\dfrac{4}{3}.20.\dfrac{1}{5}.\dfrac{3}{4}\\=\dfrac{1.4.20.1.3}{2.3.5.4}\\=2$