Question

tìm số nguyên x,y sao cho

1/2 < x/10 < y/5 < 1

giúp mình với , mai mình thi rồi

Answer 1

\(\dfrac{1}{2}< \dfrac{x}{10}< \dfrac{y}{5}< 1\)

=>\(\dfrac{5}{10}< \dfrac{x}{10}< \dfrac{2y}{10}< \dfrac{10}{10}\)

=>5<x<2y<10

=>\(\left(x;2y\right)\in\left\{\left(6;7\right);\left(6;8\right);\left(6;9\right);\left(7;8\right);\left(7;9\right);\left(8;9\right)\right\}\)

=>\(\left(x;y\right)\in\left\{\left(6;\dfrac{7}{2}\right);\left(6;4\right);\left(6;\dfrac{9}{2}\right);\left(7;4\right);\left(7;\dfrac{9}{2}\right);\left(8;\dfrac{9}{2}\right)\right\}\)

mà x,y nguyên

nên \(\left(x;y\right)\in\left\{\left(6;4\right);\left(7;4\right)\right\}\)