Question

tìm x

a) \(2\frac{2}{9}\)x=1/12+1/20+1/30+1/42+1/56+1/72

b) ( 1/2.3+1/3.4+.....+1/45.50)x=1

Answer 1

a,\(2\frac{2}{9}x=\frac{1}{12}+\frac{1}{20}+............+\frac{1}{72}\)

=>\(\frac{20}{9}x=\frac{1}{3.4}+\frac{1}{4.5}+.............+\frac{1}{8.9}\)

=>\(\frac{20}{9}x=\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+.............+\frac{1}{8}-\frac{1}{9}\)

=>\(\frac{20}{9}x=\frac{1}{3}-\frac{1}{9}\)

=>\(\frac{20}{9}x=\frac{2}{9}\)

=>x=\(\frac{1}{10}\)

b,\(\left(\frac{1}{2.3}+\frac{1}{3.4}+.............+\frac{1}{45.50}\right)x=1\)

=>\(\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...........+\frac{1}{45}-\frac{1}{50}\right)x=1\)

=>\(\left(\frac{1}{2}-\frac{1}{50}\right)x=1\)

=>\(\frac{12}{25}x=1\)

=>\(x=\frac{25}{12}\)

Answer 2

ko phải là ha ji won mà là hari won