bài 7:tính bằng cách thuận tiện nhất

a, 1/3+2/3...+3\(\frac{1}{3}\) + 3\(\frac{2}{3}\) =.......

b,9+9/2+9/4+9/8......+9/128+9/256=......

c,\(\frac{5}{3}\) +     \(\frac{5}{3\cdot5}\) +    \(\frac{5}{5\cdot7}\) + ......... +\(\frac{5}{101\cdot103}\) =.........

Tìm x

a \(\frac{3}{4}+\frac{1}{4}xX=2\)

b X - \(\frac{2}{3}x\frac{9}{4}=2,5-\frac{1}{2}\)

c \(2xX+\frac{1}{3}=\frac{4}{3}\)

d \(X:\frac{2}{3}+0,75=\frac{9}{4}+3\)

e \(\frac{6}{4}:X+\frac{1}{2}=\frac{9}{4}x\frac{2}{3}\)

f \(Xx\frac{3}{5}-\frac{2}{5}=3\frac{3}{4}-1\)

1 tính

3+\(\frac{2}{5}\)-\(\frac{3}{4}\)x\(\frac{4}{5}\)

5-\(\frac{7}{9}\)+\(\frac{2}{3}\)-\(\frac{5}{6}\)/ \(\frac{4}{9}\)

\(5\frac{1}{5}\)+\(\frac{4}{5}\)/ (2-\(\frac{2}{3}\))x3

baì 1:tính nhanh nếu có thể:

a,(\(10\frac{2}{9}+2\frac{3}{5}\)) _\(6\frac{2}{9}\)

b,\(\frac{-1}{6}-\frac{2}{3}.\frac{75}{100}+\frac{\left(-2\right)^2}{5}\)

1, Tìm X

\(1\)- (   \(6\frac{5}{9}\)+ X - \(6\frac{6}{18}\)) : \(12\frac{1}{9}\) = 0

2 , Tìm số tự nhiên có 2 chữ số ab sao cho

ab  = ba x 3 + 5

tính nhanh

\(a,\frac{11}{15}+\frac{5}{7}+\frac{2}{7}+\frac{4}{15}\)

\(b,\frac{5}{9}x\frac{1}{2}+\frac{5}{9}x\frac{6}{4}\)

\(c,\frac{7}{8}:\frac{1}{2}+\frac{9}{8}:\frac{1}{2}\)

\(d,\frac{17}{10}+\frac{1}{2}-\frac{7}{10}\)