6,5       

a: \(=347\cdot4\cdot9\cdot400:8=347\cdot36\cdot50=624600\)

c: \(=16:\left\{400:\left[200-37-138\right]\right\}\)

\(=16:\left\{400:25\right\}=16:16=1\)

e: \(=46-\left[300:15\right]-2=46-20-2=24\)

A.\(\dfrac{4}{20}\)+\(\dfrac{16}{42}\)+\(\dfrac{6}{15}\)+\(\dfrac{-3}{5}\)+\(\dfrac{2}{21}\)+\(\dfrac{-10}{21}\)+\(\dfrac{3}{20}\)

=\(\dfrac{1}{5}\)+\(\dfrac{8}{21}\)+\(\dfrac{6}{15}\)+\(\dfrac{-3}{5}\)+\(\dfrac{2}{21}\)+\(\dfrac{-10}{21}\)+\(\dfrac{3}{20}\)

=\((\dfrac{1}{5}\)+\(\dfrac{6}{15}\)+\(\dfrac{-3}{5}\)\()\)+\((\dfrac{8}{21}\)+\(\dfrac{2}{21}\)+\(\dfrac{-10}{21}\)\()\)+\(\dfrac{3}{20}\)

=\((\)\(\dfrac{1}{5}\)+\(\dfrac{2}{5}\)+\(\dfrac{-3}{5}\)\()\)+ 0 +\(\dfrac{3}{20}\)

= 0 + 0 +\(\dfrac{3}{20}\)

=\(\dfrac{3}{20}\)

B.\(\dfrac{42}{46}\)+\(\dfrac{250}{286}\)+\(\dfrac{-2121}{2323}\)+\(\dfrac{-125125}{143143}\)

=\(\dfrac{21}{23}\)+\(\dfrac{125}{143}\)+\(\dfrac{-21}{23}\)+\(\dfrac{-125}{134}\)

=\((\dfrac{21}{23}+\dfrac{-21}{23})+(\dfrac{125}{143}+\dfrac{-125}{134})\)

= 0 + 0

= 0

Chúc bạn Tran Mai học tốt nha

nick mình đi

Tổng của chiều dài và chiều rộng là: 

71,4:2=35,7(m)

Chiều rộng là:

35,7 . 4/7=20,4(m)

Chiều dài là:

35,7-20,4=15,3(m)

Diện tích là:

20,4 . 15,3=312,12(m²)

Gọi độ dài 2 cạnh hình chữ nhật là a và b.

Theo đề bài ta có: 

(a+ b)2= 71,4      => a+b = 142,8

a/4= b/7 

Áp dụng tính chất của dãy tỉ số bằng nhau:

Đến đây chắc dễ rồi.... 

46- (16+714:15)-2

= 46-(16+47,6)-2

= 46-63,6-2

=-19.6

số đó à 

-2

mình chỉ chắc thế

thôi chứ đề bài hình như 

bn chép sai

d) \(\sqrt{46+6\sqrt{5}}=\sqrt{45+2\cdot3\sqrt{5}+1}=\sqrt{\left(3\sqrt{5}\right)^2+2\cdot3\sqrt{5}+1}=\sqrt{\left(3\sqrt{5}+1\right)^2}=\left|3\sqrt{5}+1\right|=3\sqrt{5}+1\)

e) \(\sqrt{9+4\sqrt{2}}=\sqrt{8+2\cdot2\sqrt{2}+1}=\sqrt{\left(2\sqrt{2}\right)^2+2\cdot2\sqrt{2}+1}=\sqrt{\left(2\sqrt{2}+1\right)^2}=\left|2\sqrt{2}+1\right|=2\sqrt{2}+1\)

f) \(\sqrt{16+2\sqrt{15}}=\sqrt{15+2\sqrt{15}+1}=\sqrt{\left(\sqrt{15}+1\right)^2}=\left|\sqrt{15}+1\right|=\sqrt{15}+1\)

d

\(=\sqrt{45+\sqrt{180}+1}=\sqrt{45+\sqrt{36.5}+1}=\sqrt{45+6\sqrt{5}+1}\\ =\sqrt{\left(\sqrt{45}\right)^2+6\sqrt{5}+1}=\sqrt{\left(\sqrt{45}+1\right)^2}=\sqrt{45}+1\)

e

\(=\sqrt{8+\sqrt{32}+1}=\sqrt{8+\sqrt{4.8}+1}=\sqrt{\left(\sqrt{8}\right)^2+2\sqrt{8}+1^2}=\sqrt{\left(\sqrt{8}+1\right)^2}=\sqrt{8}+1\)

f

\(\sqrt{15+2\sqrt{15}+1}=\sqrt{\left(\sqrt{15}+1\right)^2}=\sqrt{15}+1\)

1: \(347\cdot2^2-2^2\cdot\left(216+184\right):8\)

\(=347\cdot4-4\cdot400:8\)

\(=347\cdot4-4\cdot50=4\cdot\left(347-50\right)=4\cdot297=1188\)

2: \(132-\left\lbrack116-\left(132-128\right)^2\right\rbrack\)

\(=132-\left\lbrack116-4^2\right\rbrack\)

=132-(116-16)

=132-100

=32

3: \(16:\left\lbrace400:\left\lbrack200-\left(37+46\cdot3\right)\right\rbrack\right\rbrace\)

=16:{400:[200-(37+138)]}

=16:{400:[200-175]}

=16:{400:25}

=16:16

=1

4: \(\left\lbrace184:\left\lbrack96-124:31\right\rbrack-2\right\rbrace\cdot3651\)

\(=\left\lbrace\frac{184}{96-4}-2\right\rbrace\cdot3651\)

=(184:92-2)*3651

=0

5: \(46-\left\lbrack\left(16+71\cdot4\right):15\right\rbrack-2\)

=46-[(16+284):15]-2

=46-300:15-2

=46-20-2

=46-22

=24

6: \(3^3\cdot18+72\cdot4^2-41\cdot18\)

\(=18\left(3^3-41\right)+72\cdot16\)

\(=18\cdot\left(27-41\right)+18\cdot64\)

=18(-14+64)

=18*50

=900

7: \(\left(56\cdot46-25\cdot23\right):23\)

\(=56\cdot\frac{46}{23}-25\)

=112-25

=87

8: \(\left(28\cdot54+56\cdot36\right):21:2\)

\(=18\cdot28\left(3+2\cdot2\right):42\)

\(=18\cdot\frac{28}{42}\cdot7=18\cdot\frac23\cdot7=12\cdot7=84\)

9: \(\left(76\cdot34-19\cdot64\right):\left(38\cdot9\right)\)

\(=\frac{19\cdot\left(4\cdot34-64\right)}{38\cdot9}=\frac{4\cdot34-64}{9\cdot2}=\frac{4\cdot\left(34-16\right)}{18}=4\)

10: \(\left(2+4+6+\cdots+100\right)\cdot\left(36\cdot333-108\cdot111\right)\)

\(=\left(2+4+6+\cdots+100\right)\cdot36\cdot111\left(3-3\right)\)

=0

11: \(\left(5\cdot4^{11}-3\cdot16^5\right):4^{10}\)

\(=\left(5\cdot4^{11}-3\cdot4^{10}\right):4^{10}\)

\(=5\cdot\frac{4^{11}}{4^{10}}-3\cdot\frac{4^{10}}{4^{10}}\)

=20-3

=17

12: \(\frac{7256\cdot4375-725}{3650+4375\cdot7255}=\frac{7255\cdot4375+4375-725}{7255\cdot4375+3650}\)

\(=\frac{7255\cdot4375+3650}{7255\cdot4375+3650}\)

=1