Độ dài đoạn BC là:

   12 : 4 + 2,3 = 5,3 (cm)

Chu vi của ABCD  là:

  (5 + 4 + 5,3) x 2 = 28,6 (cm)

Diện tích ABCD là:

   9 x 5,3 = 47,4 (cm²)

Đáp số:...

Độ dài BC:

2,3 + 12:4 = 5,3(cm)

Độ dài CD:

5 + 4 = 9 (cm)

Diện tích ABCD:

9 x 5,3= 47,7 (cm²)

Chu vi ABCD:

(5,3 + 9) x 2 = 28,6 (cm)

Đ.số:.....

6 tấn 8 tạ = 6000 + 800 = 6800 kg

6 tấn 8 tạ =6800kg

a; 576 + 678 + 780 - 475 - 577 - 679

= (576 - 475) + (678 - 577) + (780  - 679)

= 101 + 101 + 101

= 101 x 3 

= 303 

b; (126 + 32) x (18  - 16 - 2)

= (126 + 32) x ( 2 - 2)

= (126 + 32) x 0

= 0

\(x\) - (10 - \(x\)) = \(x\) - 22

\(x\) - 10 + \(x\) = \(x\) - 22

2\(x\) - 10 = \(x\) - 22

2\(x\) - \(x\)  = -22 + 10

\(x\)         = - 12

Dạ,em cảm ơn cô ạ!

\(\left(\dfrac{1}{4}+35\%+0,65+75\%\right)\times\left(1\dfrac{6}{9}+4\dfrac{8}{24}\right)\)

\(=\left(0,25+0,35+0,65+0,75\right)\times\left(1+\dfrac{2}{3}+4+\dfrac{1}{3}\right)\)

\(=2\times6\)

\(=12\)

\(\left(\dfrac{1}{4}+35\%+0,65+75\%\right)\times\left(1\dfrac{6}{9}+4\dfrac{8}{24}\right)\)

\(=\left(\dfrac{1}{4}+\dfrac{7}{20}+\dfrac{65}{100}+\dfrac{3}{4}\right)\times\left(\dfrac{15}{9}+\dfrac{13}{3}\right)\)

\(=\left(\dfrac{5}{20}+\dfrac{7}{20}+\dfrac{13}{20}+\dfrac{15}{20}\right)\times6\)

\(=\left[\left(\dfrac{15}{20}+\dfrac{5}{20}\right)+\left(\dfrac{7}{20}+\dfrac{13}{20}\right)\right]\times6\)

\(=2\times6\)

\(=12\)

Đề không rõ ràng. Bạn xem lại nhé.

Bài 9

a; A = (1 + \(\dfrac{1}{3}\))\(\times\)(1 + \(\dfrac{1}{8}\))\(\times\)(1 + \(\dfrac{1}{15}\))\(\times\)...\(\times\)(1 + \(\dfrac{1}{9999}\))

    A = \(\dfrac{3+1}{3}\)\(\times\)\(\dfrac{8+1}{8}\)\(\times\)\(\dfrac{15+1}{15}\)\(\times\)...\(\times\)\(\dfrac{9999+1}{9999}\)

   A  = \(\dfrac{4}{3}\)\(\times\)\(\dfrac{9}{8}\)\(\times\)\(\dfrac{16}{15}\)\(\times\)...\(\times\)\(\dfrac{10000}{9999}\)

A = \(\dfrac{2\times2\times3\times3\times4\times4\times...\times100\times100}{1\times3\times2\times4\times3\times5\times...\times99\times101}\)

A = \(\dfrac{2\times100}{1\times101}\)

A = \(\dfrac{200}{101}\)

b; B = (1 - \(\dfrac{1}{4}\))\(\times\) (1 - \(\dfrac{1}{9}\)) \(\times\) (1 - \(\dfrac{1}{16}\))\(\times\)...\(\times\)(1 - \(\dfrac{1}{10000}\))

    B = \(\dfrac{4-1}{4}\) \(\times\) \(\dfrac{9-1}{9}\) \(\times\) \(\dfrac{16-1}{16}\) \(\times\) \(\dfrac{10000-1}{10000}\)

    B = \(\dfrac{3}{4}\)\(\times\) \(\dfrac{8}{9}\)\(\times\)\(\dfrac{15}{16}\)\(\times\)...\(\times\) \(\dfrac{9999}{10000}\)

   B = \(\dfrac{1\times3}{2\times2}\)\(\times\)\(\dfrac{2\times4}{3\times3}\)\(\times\)\(\dfrac{3\times5}{4\times4}\)\(\times\)...\(\times\)\(\dfrac{99\times101}{100\times100}\)

  B = \(\dfrac{1\times101}{2\times100}\)

  B = \(\dfrac{101}{200}\)

\(-35-2x=-19\\\Rightarrow2x=-35-(-19)\\\Rightarrow2x=-35+19\\\Rightarrow2x=-16\\\Rightarrow x=-16:2\\\Rightarrow x=-8\\Vậy:x=-8.\)

−35−2x=−19

⇒2x=−35−(−19)

⇒2x=−35+19

⇒2x=−16

⇒x=−16:2

⇒x=−8

Vậy:x=−8.

Chiều dài hình chữ nhật là:

$36:\frac35=60(cm)$

Độ dài sợi dây thép là:

$(60+36)\times2=192(cm)$

Đ/s: $192cm$.