ket ban voi toi di ma

toi hoc n** qua

x=266:7,6

x=35

x=266 :  7,6

x=35

17 - x = 286 - 266

17 - x = 20

x = 17 - 20

x = -3

$\frac{1}{20}+\frac{2}{35}+\frac{3}{70}+\frac{4}{140}+\frac{5}{266}+\frac{6}{475}$

$=(\frac{1}{20}+\frac{3}{70}+\frac{4}{140})+(\frac{2}{35}+\frac{5}{266}+\frac{6}{475})$

$=\frac{17}{140}+\frac{31}{350}$

$=\frac{21}{100}$

A = \(\dfrac{1}{20}\) + \(\dfrac{2}{35}\) + \(\dfrac{3}{70}\) + \(\dfrac{4}{140}\) + \(\dfrac{5}{266}\) + \(\dfrac{6}{475}\)

A = \(\dfrac{1}{4\times5}\)+ \(\dfrac{2}{5\times7}\)+ \(\dfrac{3}{7\times10}\)+ \(\dfrac{4}{10\times14}\)+\(\dfrac{5}{14\times19}\)+\(\dfrac{6}{19\times25}\)

A = \(\dfrac{1}{4}\)-\(\dfrac{1}{5}\)+\(\dfrac{1}{5}\)-\(\dfrac{1}{7}\)+\(\dfrac{1}{7}\)-\(\dfrac{1}{10}\)+\(\dfrac{1}{10}\)+\(\dfrac{1}{10}\)-\(\dfrac{1}{14}\)+\(\dfrac{1}{14}\)-\(\dfrac{1}{19}\)+\(\dfrac{1}{19}\)-\(\dfrac{1}{25}\)

A = \(\dfrac{1}{4}\)-\(\dfrac{1}{25}\)

A = \(\dfrac{21}{100}\)

1366+275-266-175

=(1366-266)+(275-175)

=1100+100

=1200

1366+275-266-175

=1366-266+275-175

=1100+100

=1200

( 532×7 − 266 × 14 ) × ( 532 × 7 + 266 )

= ( 266 × 2 × 7 − 266 × 14 ) × ( 532 × 7 + 266 )

= ( 266 × 14 − 266 × 14 ) × ( 532 × 7 + 266 )

= 0 × 7 x ( 532 × 7 + 266 )

= 0

( 532 x 7 - 266 x 14 ) x ( 532 x 7 + 266 )

= ( 532 x 7 - 266 x 14 ) x ( 532 x 7 + 266 ) { cậu gạch số 14 và 7 in đậm và gạch chân }

= ( 532 x 1 - 266 x 2 ) x ( 532 x 7 + 266 ) { vì 14 : 7 =2 và 7 : 7 =1 }

= ( 532 - 532 )  x ( 532 x 7 + 266 )

= 0  x ( 532 x 7 + 266 )

= 0

Cậu ko phải ghi chỗ { ..... } đâu nha .

= 948 * 113 + 43 * 113 + 113 * 1

= (948 + 43 + 1) * 113

= 992 * 113

= 112096

\(948.113+43.113+113.1\)

\(=113.\left(948+43+1\right)\)

\(=113.992=112096\)