Question

bài 1 tính nhanh 

ví dụ 3/8+5/7+45/72+22/77

=(3/8+45/72)+(5/7+22/77)

=      1           +       1

=                  2

a, 1/2x2/7+3/7:2+1/2:7/2                                                          b, 3/7x3/5+3/5:7+3/7:5/3

                                                 các bạn giải rõ giúp mình nhé, mình đang cần gấp

Answer 1

a, \(\frac{1}{2}x\frac{2}{7}+\frac{3}{7}:2+\frac{1}{2}:\frac{7}{2}\)

= \(\frac{1}{2}x\frac{2}{7}+\frac{3}{7}x\frac{1}{2}+\frac{1}{2}x\frac{2}{7}\)

= \(\frac{1}{2}x\left(\frac{2}{7}+\frac{3}{7}+\frac{2}{7}\right)\)

= \(\frac{1}{2}x1\)

= \(\frac{1}{2}\)

Answer 2

\(a,\frac{1}{2}x\frac{2}{7}+\frac{3}{7}:2+\frac{1}{2}:\frac{7}{2}\)

\(=\frac{1}{2}x\frac{2}{7}+\frac{3}{7}x\frac{1}{2}+\frac{1}{2}x\frac{2}{7}\)

\(=\frac{1}{2}x\left(\frac{2}{7}+\frac{3}{7}+\frac{2}{7}\right)\)

\(=\frac{1}{2}x1\)

\(=\frac{1}{2}\)

\(b,\frac{3}{7}x\frac{3}{5}+\frac{3}{5}:7+\frac{3}{7}:\frac{5}{3}\)

\(=\frac{3}{7}x\frac{3}{5}+\frac{3}{5}x\frac{1}{7}+\frac{3}{7}x\frac{3}{5}\)

\(=\frac{3}{5}x\left(\frac{3}{7}+\frac{1}{7}+\frac{3}{7}\right)\)

\(=\frac{3}{5}x1\)

\(=\frac{3}{5}\)

Answer 3

b, \(\frac{3}{7}x\frac{3}{5}+\frac{3}{5}:7+\frac{3}{7}:\frac{5}{3}\)

= \(\frac{3}{7}x\frac{3}{5}+\frac{3}{5}x\frac{1}{7}+\frac{3}{7}x\frac{3}{5}\)

= \(\frac{3}{5}x\left(\frac{3}{7}+\frac{1}{7}+\frac{3}{7}\right)\)

= \(\frac{3}{5}x1\)

= \(\frac{3}{5}\)