Question

Tính nhanh : 

 254 . 399 - 145

254+399x253
 

Answer 1

 = ( 253 + 1) . 399 - 145

    254 + 399 x 253

= 253 . 399 + 1 . 399 - 145

   254 + 399 x 253

= 253 . 399 + 254

  254 + 399 . 253

= 1

Answer 2

\(\frac{254.399-145}{254+399.253}=\frac{253.399+399-145}{399.253+254}=\frac{253.399+254}{399.253+154}=1\)