lm ơn ik có ai giúp me ko me cần gấp

ai mà giúp tui thả tim hết dù đúng hay sai

7² - 36 : 3²

= 49 - 36 : 9

= 49 - 4

= 45

150 - [10² - (14 -11)² . 2007⁰   ]

= 150 - [100 - (14 -11)². 1]

= 150 - [100 - 3² .1]

= 150 - [100 - 9 .1]

= 150 - 91

= 59

59 - [90 - (17 - 8)²   ]

= 59 - [90 - 9²   ]

= 59 - [90 - 81]

= 59 - 9

= 50

Bài có sai sót gì mong bạn thông cảm.

a,6

b,-200

c,1900

d,-900000

k mình nha 

mình cần gấp

 16 . ( 38 - 2 ) - 38 . ( 16 - 1 )

=16 . 38 - 2 .16 - 38 .16 - 1.38

=16.38.(2.16-1.38)

=608.(32-38)

=608.(-6)

=-3648

1 a, 16.38-16.2-38.16-38.1=608-32-608-38=-70 t

Ta có: \(\dfrac{1}{2}+\dfrac{5}{6}+\dfrac{11}{12}+\dfrac{19}{20}+\dfrac{41}{42}+\dfrac{55}{56}+\dfrac{71}{72}+\dfrac{89}{90}\)

\(=8-\left(\dfrac{1}{2}+\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{20}+\dfrac{1}{42}+\dfrac{1}{56}+\dfrac{1}{72}+\dfrac{1}{90}\right)\)

\(=8-\left(\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}+...+\dfrac{1}{8}-\dfrac{1}{9}+\dfrac{1}{9}-\dfrac{1}{10}\right)\)

\(=8-1+\dfrac{1}{10}\)

\(=\dfrac{71}{10}\)

=1−1/2+1−1/6+1−1/12+1−1/20+1−1/30+1−1/42+1−1/56+1−1/72+1−1/90

=9-(1-1/2+1/2-1/3+.....+1/9-1/10)

\(A=\dfrac{1}{2}+\dfrac{5}{6}+\dfrac{11}{12}+\dfrac{29}{30}+\dfrac{41}{42}+\dfrac{55}{56}+\dfrac{71}{72}+\dfrac{89}{90}\) (sửa đề)

\(=\left(1-\dfrac{1}{2}\right)+\left(1-\dfrac{1}{6}\right)+\left(1-\dfrac{1}{12}\right)+\left(1-\dfrac{1}{30}\right)+\left(1-\dfrac{1}{42}\right)+\left(1-\dfrac{1}{56}\right)+\left(1-\dfrac{1}{72}\right)+\left(1-\dfrac{1}{90}\right)\)

\(=\left(1+1+1...+1\right)-\left(\dfrac{1}{2}+\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{30}+\dfrac{1}{42}+\dfrac{1}{56}+\dfrac{1}{72}+\dfrac{1}{90}\right)\)

\(=8-\left(\dfrac{1}{1\cdot2}+\dfrac{1}{2\cdot3}+\dfrac{1}{3\cdot4}+...+\dfrac{1}{9\cdot10}\right)\) ( có 8 số hạng 1)

\(=8-\left(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{9}-\dfrac{1}{10}\right)\)

\(=8-\left(1-\dfrac{1}{10}\right)\)

\(=8-\dfrac{9}{10}\)

\(=\dfrac{80}{10}-\dfrac{9}{10}=\dfrac{71}{10}\)

\(9-A=1-\frac{1}{2}+1-\frac{5}{6}+1-\frac{11}{12}+1-\frac{19}{20}+...+1-\frac{89}{90}\)

\(\Leftrightarrow9-A=\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+...+\frac{1}{9\cdot10}\)

\(\Leftrightarrow9-A=\frac{2-1}{1\cdot2}+\frac{3-2}{2\cdot3}+\frac{4-3}{3\cdot4}+...+\frac{10-9}{9\cdot10}\)

\(\Leftrightarrow9-A=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{4}-\frac{1}{4}+...+\frac{1}{9}-\frac{1}{10}=1-\frac{1}{10}=\frac{9}{10}\)

\(\Leftrightarrow A=9-\frac{9}{10}=\frac{81}{10}\)

1/2+5/6+11/12+19/20+29/30+41/42+55/56+71/72=(1-1/2)+(1-1/6)+(1-1/12)+(1-1/20)+(1-1/30)+(1-1/42)+(1-1/56)+(1-1/72)=(1+1+1+1+1+1+1+1)-(1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72)=8-(1/1.2+1/2.3+1/3.4+1/4.5+1/5.6+1/6.7+1/7.8+1/8.9)=8-(1-1/2+1/2-1/3+...+1/8-1/9)=8-(1-1/9)=8-8/9=72/9-8/9=64/9

1/2+5/6+11/12+19/20+29/30+41/42+55/56+71/72

=10-(1/2+1/6+..+1/110)

=10-(1/1x2+1/2x3+...+1/10x11)

=10-(1-1/2+1/2-1/3+...+1/10-1/11)

=10-(1-1/11)

=10-10/11

=100/11