Tính: \(-\frac{12}{15} + \frac{4}{26}\)
không cần làm hết thanks
----- Nội dung ảnh -----
**Bài toán 3: Tính**
a) \(-\frac{12}{15} + \frac{4}{26}\)
b) \(-\frac{1}{21} - \frac{1}{14}\)
c) \(-\frac{1}{9} + \frac{5}{12}\)
d) \(\frac{5}{8} - \frac{7}{10}\)
**Bài toán 4: Tính**
a) \(1 - \left( \frac{1}{12} - \frac{1}{4} \right)\)
b) \(\frac{3}{7} + \left(-\frac{5}{2}\right) + \left(-\frac{3}{5}\right)\)
c) \(\frac{4}{5} + \frac{7}{10}\)
d) \(\frac{2}{5} + \left(-\frac{4}{3}\right) + \left(-\frac{1}{2}\right)\)
e) \(-\frac{1}{24} \left[ \frac{1}{4} - \left( 1 - \frac{2}{7} \right) \right]\)
f) \(\left( \frac{5}{7} - \frac{7}{5} \right) - \left[ \frac{1}{2} - \left( \frac{2}{7} + \frac{1}{10} \right) \right]\)
**Bài toán 5: Tìm x, bi t:**
a) \(x - \frac{1}{5} - \frac{3}{6} = 1\)
b) \(\frac{16}{5} - x = \frac{4}{5} - \frac{3}{10}\)
c) \(\frac{1}{20} - \left( x - \frac{8}{5} \right) = \frac{1}{10}\)
d) \(x + \frac{1}{3} = \frac{2}{5} + \frac{3}{2}\)
e) \(\left( \frac{3}{8} - \frac{1}{5} \right) \left( \frac{5}{8} - x \right) = \frac{1}{5}\)
**Bài toán 6: Tìm x, bi t:**
a) \(|x + 1| - \frac{2}{3} = \frac{1}{5}\)
b) \(|x + \frac{3}{4}| + \frac{1}{3} = \frac{5}{6}\)
c) \(\frac{9}{2} \left[ \frac{2}{3} - \left( x + \frac{7}{4} \right) \right] = -\frac{5}{4}\)
d) \(\frac{4}{3} \left( x - \frac{1}{5} \right) = -\frac{3}{10} + \frac{1}{2} - \frac{1}{6}\)
**Bài toán 7: Tính:**
a) \(\frac{1}{4} + \left| \frac{1}{3} - 5 \left( -\frac{5}{12} \right) + \frac{1}{2} \right|\)
b) \(3 - \frac{3}{4} + \left| -\frac{1}{10} - \frac{3}{20} \right|\)
c) \(\frac{3}{4} \left( \frac{12}{8} - \frac{15}{2} + \frac{6}{20} \right)\)
d) \(-\left| \frac{6}{5} - \frac{1}{2} - \left( \frac{3}{4} - \frac{5}{8} \right) - \frac{3}{2} \right|\)
**Bài toán 8: Tính nhanh**
a) \(A = \frac{1}{1.2} + \frac{1}{2.3} + \ldots + \frac{1}{2019.2020}\)
b) \(B = \frac{1}{9.10} + \frac{1}{8.9} + \frac{1}{2.3} + \frac{1}{1.2}\)
c) \(C = \frac{1}{3.5} + \frac{1}{5.7} + \ldots + \frac{1}{2017.2019}\)
----- Nội dung ảnh -----
**Bài toán 3: Tính**
a) \(-\frac{12}{15} + \frac{4}{26}\)
b) \(-\frac{1}{21} - \frac{1}{14}\)
c) \(-\frac{1}{9} + \frac{5}{12}\)
d) \(\frac{5}{8} - \frac{7}{10}\)
**Bài toán 4: Tính**
a) \(1 - \left( \frac{1}{12} - \frac{1}{4} \right)\)
b) \(\frac{3}{7} + \left(-\frac{5}{2}\right) + \left(-\frac{3}{5}\right)\)
c) \(\frac{4}{5} + \frac{7}{10}\)
d) \(\frac{2}{5} + \left(-\frac{4}{3}\right) + \left(-\frac{1}{2}\right)\)
e) \(-\frac{1}{24} \left[ \frac{1}{4} - \left( 1 - \frac{2}{7} \right) \right]\)
f) \(\left( \frac{5}{7} - \frac{7}{5} \right) - \left[ \frac{1}{2} - \left( \frac{2}{7} + \frac{1}{10} \right) \right]\)
**Bài toán 5: Tìm x, bi t:**
a) \(x - \frac{1}{5} - \frac{3}{6} = 1\)
b) \(\frac{16}{5} - x = \frac{4}{5} - \frac{3}{10}\)
c) \(\frac{1}{20} - \left( x - \frac{8}{5} \right) = \frac{1}{10}\)
d) \(x + \frac{1}{3} = \frac{2}{5} + \frac{3}{2}\)
e) \(\left( \frac{3}{8} - \frac{1}{5} \right) \left( \frac{5}{8} - x \right) = \frac{1}{5}\)
**Bài toán 6: Tìm x, bi t:**
a) \(|x + 1| - \frac{2}{3} = \frac{1}{5}\)
b) \(|x + \frac{3}{4}| + \frac{1}{3} = \frac{5}{6}\)
c) \(\frac{9}{2} \left[ \frac{2}{3} - \left( x + \frac{7}{4} \right) \right] = -\frac{5}{4}\)
d) \(\frac{4}{3} \left( x - \frac{1}{5} \right) = -\frac{3}{10} + \frac{1}{2} - \frac{1}{6}\)
**Bài toán 7: Tính:**
a) \(\frac{1}{4} + \left| \frac{1}{3} - 5 \left( -\frac{5}{12} \right) + \frac{1}{2} \right|\)
b) \(3 - \frac{3}{4} + \left| -\frac{1}{10} - \frac{3}{20} \right|\)
c) \(\frac{3}{4} \left( \frac{12}{8} - \frac{15}{2} + \frac{6}{20} \right)\)
d) \(-\left| \frac{6}{5} - \frac{1}{2} - \left( \frac{3}{4} - \frac{5}{8} \right) - \frac{3}{2} \right|\)
**Bài toán 8: Tính nhanh**
a) \(A = \frac{1}{1.2} + \frac{1}{2.3} + \ldots + \frac{1}{2019.2020}\)
b) \(B = \frac{1}{9.10} + \frac{1}{8.9} + \frac{1}{2.3} + \frac{1}{1.2}\)
c) \(C = \frac{1}{3.5} + \frac{1}{5.7} + \ldots + \frac{1}{2017.2019}\)