Question

Tính :

a) 0,1(2) + 0,1(3)

b) 0,7(3) + 0,3(7)

Answer 1

a. \(0,1\left(2\right)=0+\frac{12-1}{90}=\frac{11}{90};0,1\left(3\right)=0+\frac{13-1}{90}=\frac{12}{90}=\frac{2}{15}\)

=> 0,1(2)+0,1(3)=11/90 + 2/15 = 11/90 + 12/90 = 23/90

b. \(0,7\left(3\right)=0+\frac{73-7}{90}=\frac{66}{90}=\frac{11}{15};0,3\left(7\right)=0+\frac{37-3}{90}=\frac{34}{90}=\frac{17}{45}\)

=> 0,7(3)+0,3(7)=11/15 + 17/45 = 33/45 + 17/45 = 50/45 = 10/9

Answer 2

a)\(0,1\left(2\right)+0,1\left(3\right)\)

=\(0,1+0,0\left(2\right)+0,1+0,0\left(3\right)\)

=\(0,2+0,0\left(1\right).2+0,0\left(1\right).3\)

=\(0,2+0,0\left(1\right).5\)

=\(0,2+\frac{1}{90}.5\)

=\(\frac{3,6}{18}+\frac{1}{18}\)

=\(\frac{4,6}{18}\)

Answer 3

a) \(0,1\left(2\right)+0,1\left(3\right)=\frac{1}{10}.1,\left(2\right)+\frac{1}{10}.1,\left(3\right)=\frac{1}{10}.\frac{11}{9}+\frac{1}{10}.\frac{4}{3}=\frac{1}{10}.\left(\frac{11}{9}+\frac{4}{3}\right)=\frac{1}{10}.\frac{23}{9}=\frac{23}{90}\)

b) \(0,7\left(3\right)+0,3\left(7\right)=\frac{1}{10}.7,\left(3\right)+\frac{1}{10}.3,\left(7\right)=\frac{1}{10}.\frac{22}{3}+\frac{1}{10}.\frac{34}{9}=\frac{1}{10}.\left(\frac{22}{3}+\frac{34}{9}\right)=\frac{1}{10}.\frac{100}{9}=\frac{10}{9}\)