Question

[you are beautiful]

tính nhanh : B = 70 . \(\left(\frac{131313}{565656}+\frac{131313}{727272}+\frac{131313}{909090}\right)\)

Answer 1

[Nguyễn Vũ Minh Hiếu]

\(B=70.\left(\frac{131313}{565656}+\frac{131313}{727272}+\frac{131313}{909090}\right)\)

\(B=70.\left(\frac{13}{56}+\frac{13}{72}+\frac{13}{90}\right)\)

\(B=70.13.\left(\frac{1}{56}+\frac{1}{72}+\frac{1}{90}\right)\)

\(B=910.\left(\frac{1}{7.8}+\frac{1}{8.9}+\frac{1}{9.10}\right)\)

\(B=910.\left(\frac{1}{7}-\frac{1}{8}+\frac{1}{8}-\frac{1}{9}+\frac{1}{9}-\frac{1}{10}\right)\)

\(B=910.\left[\frac{1}{7}+\left(\frac{1}{8}-\frac{1}{8}\right)+\left(\frac{1}{9}-\frac{1}{9}\right)-\frac{1}{10}\right]\)

\(B=910.\left[\frac{1}{7}-\frac{1}{10}\right]\)

\(B=910.\frac{3}{70}=39\)

~ Hok tốt ~

Answer 2

[T.Ps]

#)Giải :

\(B=70.\left(\frac{131313}{565656}+\frac{131313}{727272}+\frac{131313}{909090}\right)\)

\(B=70.\left(\frac{13}{56}+\frac{13}{72}+\frac{13}{90}\right)\)( cùng chia cho 10101 )

\(B=70.\frac{39}{70}\)

\(B=39\)( trên dưới tử mẫu có 70 => loại )

        #~Will~be~Pens~#