Question

tìm x biết:
\(\dfrac{1}{3}\)+\(\dfrac{3}{35}\)<\(\dfrac{x}{210}\)<\(\dfrac{4}{7}\)+\(\dfrac{3}{5}\)+\(\dfrac{1}{3}\)

Answer 1

\(\Leftrightarrow\dfrac{70+18}{210}< \dfrac{x}{210}< \dfrac{120}{210}+\dfrac{126}{210}+\dfrac{70}{210}\)

=>88<x<316

hay \(x\in\left\{89;90;...;314;315\right\}\)

Answer 2

\(\dfrac{1}{3}+\dfrac{3}{35}=\dfrac{44}{105}=\dfrac{88}{210}\)

\(\dfrac{4}{7}+\dfrac{3}{5}+\dfrac{1}{3}=\dfrac{60}{105}+\dfrac{63}{105}+\dfrac{35}{105}=\dfrac{158}{105}=\dfrac{316}{210}\)

=> \(\dfrac{88}{210}< \dfrac{x}{210}< \dfrac{316}{210}\)

=> 88<x<316

Answer 3

`1/3 + 3/35 < x/210 < 4/7 + 3/5 + 1/3`

`70/210 + 18/210 < x/210 < 120/210 + 126/210 + 70/210`

`(70+18)/210 < x/210 < (120+126+70)/210`

`88/210 < x/210 < 316/210`

`=> 88 < x < 316`

`=> x ∈ {89,90,......314,315}`