Question

BT1; Tính

a,\(\frac{-5}{7}\)+\(\frac{2}{7}\)+\(\frac{4}{-9}\)+\(\frac{4}{9}\)

b,(\(\frac{1}{2}\):\(\frac{3}{4}\))²

c,\(\frac{1}{2}\)+\(\frac{3}{4}\)-(\(\frac{4}{5}\)+\(\frac{3}{4}\))

d,5⁶:5⁴+2³.2²-225:15²

e,\(\frac{7}{23}\)+\(\frac{4}{17}\)-\(\frac{7}{23}\)+\(\frac{13}{17}\)

g,19\(\frac{1}{4}\).\(\frac{7}{12}\)-15\(\frac{1}{4}\).\(\frac{7}{12}\)

Answer 1

Bài 1:

a) Ta có: \(\frac{-5}{7}+\frac{2}{7}+\frac{4}{-9}+\frac{4}{9}\)

\(=-\frac{3}{7}+\frac{-4}{9}+\frac{4}{9}\)

\(=-\frac{3}{7}\)

b) Ta có: \(\left(\frac{1}{2}:\frac{3}{4}\right)^2\)

\(=\left(\frac{1}{2}\cdot\frac{4}{3}\right)^2\)

\(=\left(\frac{2}{3}\right)^2=\frac{4}{9}\)

c) Ta có: \(\frac{1}{2}+\frac{3}{4}-\left(\frac{4}{5}+\frac{3}{4}\right)\)

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

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

\(=\frac{5}{10}-\frac{8}{10}=\frac{-3}{10}\)

d) Ta có: \(5^6:5^4+2^3\cdot2^2-225:15^2\)

\(=5^2+2^5-\frac{15^2}{15^2}\)

\(=25+32-1\)

\(=56\)

e) Ta có: \(\frac{7}{23}+\frac{4}{17}-\frac{7}{23}+\frac{13}{17}\)

\(=\frac{4}{17}+\frac{13}{17}\)

\(=\frac{17}{17}=1\)

g) Ta có: \(19\frac{1}{4}\cdot\frac{7}{12}-15\frac{1}{4}\cdot\frac{7}{12}\)

\(=\frac{7}{12}\left(19+\frac{1}{4}-15-\frac{1}{4}\right)\)

\(=\frac{7}{12}\cdot4=\frac{7}{3}\)