\(\frac{254x399-145}{254+399x\left(254+1\right)}\)

\(=\frac{254x399-145}{254+399x254+399}\)

\(=\frac{-145}{254+399}\)

\(=\frac{-145}{653}\)

254 × 399 - 145 / 254 + 399 × 253

= (253 + 1) × 399 - 145 / 254 + 399 × 253

= 253 × 399 + (399 - 145) / 254 + 399 × 253

= 253 × 399 + 254 / 254 + 399 × 253

= 1

\(\frac{254x399-145}{254+399x253}\)

\(=\frac{253x399+399-145}{254+399x253}\)

\(=\frac{253x399+254}{254+399x253}=1\)

\(\frac{254.399-145}{254+399.253}=\frac{254.399-145}{\left(254-1\right).399+254}\)\(=\frac{254.399-145}{254.399-399+254}=\frac{254.399-145}{254.399-145}=1\)

DẤU . LÀ DẤU NHÂN NHA

a) \(\frac{254.399-145}{254+399.253}\)

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

\(=\frac{253.399+254}{254+399.253}\)

\(=1\)

b) tự làm

\(\frac{254.399-145}{254+399.253}=\frac{\left(253+1\right).399-145}{254+399.253}=\frac{253.399+\left(399-145\right)}{254+399.253}\)

                                                                               \(=\frac{253.399+254}{254+399.253}=1\)

\(\frac{254\times399-145}{254+399\times253}\)

\(=\frac{253\times399+399-145}{254+399\times253}\)

\(=\frac{253\times399+254}{254+399\times253}\)

\(=1\)

A = \(\dfrac{254\times399-145}{254+399\times253}\)

A = \(\dfrac{\left(253+1\right)\times399-145}{254+399\times253}\)

A = \(\dfrac{253\times399+399-145}{254+399\times253}\)

A = \(\dfrac{253\times399+254}{254+399\times253}\)

A = 1 

a) \(254x399-145=\left(250+4\right)\left(400-1\right)-145\)

\(=100000+1600-250-145-4=101600-\left(250+145+4\right)\)

\(=101600-399=101201\)

b) \(254+399x253=254+\left(400-1\right)x\left(250+3\right)\)

\(=254+100000+1200-250-3\)

\(=101454-250-3=101201\)

\(\dfrac{a}{b}=1\)

(253+1)x399-145/254+399x253

=253x399+(399-145)/254+399x253

=253x399+254/254+399x253

=1

Ta có:

\(\frac{254X399-145}{254+399X253}\)

\(=\frac{\left(253+1\right)X399-154}{254+399X253}\)

\(=\frac{253X399+399-154}{254+399X253}\)

\(=\frac{253X399+254}{253X399+254}\)

\(=1\)

bang 1

     254 x399 - 145 / 254 + 399 x 255 

=  ( 253 + 1 ) x 399 - 145 / 254 + 399 x 255

=   253 x 399 + ( 399 - 145  )/ 254 + 399 x 255

=   254 x 399 + 255 / 254 + 399 x 155 

=   1

\(\frac{254.399-145}{254+399.253}\)

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

\(=\frac{253.399+254}{254+399.253}=1\)

Trả lời

254.399-145/254+399.253

=253.399+399-145/254+399.253

=253.399+254/254+399.253

=1.