`0,2 xx 317 xx 7 + 1,4 xx 352 + 331 xx 1,4`

`=1,4 xx 317 + 1,4 xx 352 + 331 xx 1,4`

`= 1,4 xx ( 317 + 352 + 331 )`

`= 1,4 xx 1000`

`= 1400`

=1400

nhanh thì chỉ có đáp án thôi

Giải:

\(\dfrac{1}{2}+\dfrac{2}{8}+\dfrac{3}{28}+\dfrac{4}{77}+\dfrac{5}{176}+\dfrac{6}{352}\) 

\(=\dfrac{1}{1.2}+\dfrac{2}{2.4}+\dfrac{3}{4.7}+\dfrac{4}{7.11}+\dfrac{5}{11.16}+\dfrac{6}{16.22}\) 

\(=\dfrac{1}{1}-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{16}+\dfrac{1}{16}-\dfrac{1}{22}\) 

\(=\dfrac{1}{1}-\dfrac{1}{22}\) 

\(=\dfrac{21}{22}\)

\(\dfrac{1}{2}+\dfrac{2}{8}+\dfrac{3}{28}+\dfrac{4}{77}+\dfrac{5}{176}+\dfrac{6}{352}\\ =\dfrac{1}{2}+\dfrac{1}{4}+\dfrac{3}{28}+\dfrac{4}{77}+\dfrac{5}{176}+\dfrac{3}{176}\\ =\dfrac{3}{4}+\dfrac{3}{28}+\dfrac{4}{77}+\dfrac{1}{22}\\ =\dfrac{21}{28}+\dfrac{3}{28}+\dfrac{7}{154}+\dfrac{8}{154}\\ =\dfrac{6}{7}+\dfrac{15}{154}\\ =\dfrac{21}{22}\)

\(\dfrac{1}{2}+\dfrac{2}{8}+\dfrac{3}{28}+\dfrac{4}{77}+\dfrac{5}{176}+\dfrac{6}{352}=\dfrac{1}{1.2}+\dfrac{2}{2.4}+\dfrac{3}{4.7}+\dfrac{4}{7.11}+\dfrac{5}{11.16}+\dfrac{6}{16.22}=1-\dfrac{1}{22}=\dfrac{21}{22}\)

a) Ta có:

Tính bằng cách thuận tiện . 

648 + 436 + 352 - 236 

= ( 648 + 352 ) + (436 - 236)

= 1000 - 200

= 800

HT

(648+352)+(436-236)

=1000+200

=1200

Chúc bạn học tốt~

  648 + 436 + 352 - 326

( 648 + 352 ) + ( 436 - 326 ) 

= 1000 + 110

= 2110

HT

phuonglebao9@gmail.com

1,4 x 317 + 1,4 x 352 + 33,1 x 14

= 1,4 x 317 + 1,4 x 352 + [ (33,1 : 0,1) x (14 x 0,1)]

= 1,4 x 317 + 1,4 x 352 + 331 x 1,4

= 1,4 x ( 317 + 352 + 331)

= 1,4 x 1000

= 1400

1,4+317+1,4x 352+331 x 14

= 1,4 x ( 317 + 352 + 331 )

= 1,4 x 1000

= 1400

Hok tốt !

a,=(202-54)(202+54)+256*352=248.*256+256*352=256*(248+352)=256*600=256*6*100=153600

b. làm tương tự

c,=5/(1+2+...+10)=5.\(\frac{10.\left(10+1\right)}{2}\)=275

(ta có công thức 1+2+...+n=\(\frac{n.\left(n+1\right)}{2}\) dễ dàng chứng minh)

A

C

A

2002 x 8648 + 2002 x 1352 + (1352-352)

=2002 x (8648+1352) + 1000

= 2002 x 10000 +1000

=20020000+1000

=20021000

Nha bạn        

2002 x 8648 + 2003 x 1352 - 352

= 2002 x 8648 + ( 2002 + 1 ) x 1352 - 352

= 2002 x 8648 + 2002 x 1352 + 1352 - 352

= 2002 x ( 8648 + 1352 ) + 1000

= 2002 x 10000 + 1000

= 20020000 + 1000 

= 20021000

2002.8648+2003.1352-352=2002.8648+(2002+1).1352-352=2002.8648+2002.1352+(2002-352)=2002(8648+1352)+1650=2002.10000+1650=20020000+1650=20021650

- 3 5 2 = - 3 2 5 2 = 9 25