Question

[Name]

làm tự luận nha

Answer 1

[ムvũ卍τเếᑎ卍ßìN꙰h̰̃❄]

câu 3:C

câu 4:A

câu 5:D

câu 6:C

câu 7:A

câu 8:A

tự luận

câu9:

a)\(\dfrac{9}{13}+\dfrac{5}{13}\)

\(=\dfrac{14}{13}\)

b)\(\dfrac{4}{9}.\dfrac{2}{6}\)

\(=\dfrac{4}{27}\)

c)\(1\dfrac{1}{3}.\left(0.5\right)+\left(\dfrac{8}{15}-\dfrac{19}{30}\right):\dfrac{6}{15}\)

\(=\dfrac{4}{3}.\dfrac{-1}{2}+\left(\dfrac{8}{15}-\dfrac{19}{30}\right):\dfrac{6}{15}\)

\(=\dfrac{4}{3}.\dfrac{-1}{2}+\dfrac{-1}{10}:\dfrac{6}{15}\)

\(=\dfrac{-2}{3}+\dfrac{-1}{4}\)

\(=\dfrac{-11}{12}\)

câu 10:

a)x-10=12

x=12+10

x=22

vậy x=22

b)\(x.\dfrac{3}{4}=\dfrac{1}{6}\)

\(x=\dfrac{1}{6}:\dfrac{3}{4}\)

\(x=\dfrac{2}{9}\)

c)\(\left(\dfrac{2}{7}.x+\dfrac{3}{7}\right):2\dfrac{1}{5}-\dfrac{3}{7}=1\)

\(\left(\dfrac{2}{7}.x+\dfrac{3}{7}\right):\dfrac{11}{5}-\dfrac{3}{7}=1\)

\(\left(\dfrac{2}{7}.x-\dfrac{3}{7}\right):\dfrac{11}{5}=1+\dfrac{3}{7}\)

\(\left(\dfrac{2}{7}.x-\dfrac{3}{7}\right):\dfrac{11}{5}=\dfrac{10}{7}\)

\(\dfrac{2}{7}.x-\dfrac{3}{7}=\dfrac{10}{7}.\dfrac{11}{5}\)

\(\dfrac{2}{7}.x-\dfrac{3}{7}=\dfrac{22}{7}\)

\(\dfrac{2}{7}.x=\dfrac{22}{7}+\dfrac{3}{7}\)

\(\dfrac{2}{7}.x=\dfrac{25}{7}\)

\(x=\dfrac{25}{7}:\dfrac{2}{7}\)

\(x=\dfrac{25}{2}\)

vậy \(x=\dfrac{25}{2}\)

câu 11:số học sinh trung bình của lớp 6a chiếm số phần trăm là:

3:4.100%=75%

số học khá của lớp 6a chiếm số phần trăm là:

100%-6,25%-75%=18,75%

câu 13

\(\dfrac{1}{2^2}+\dfrac{1}{3^2}+\dfrac{1}{4^2}+\dfrac{1}{5^2}+...+\dfrac{1}{100^2}< 1\)

vì \(\dfrac{1}{2^2}< \dfrac{1}{1.2}\)

\(\dfrac{1}{3^2}< \dfrac{1}{2.3}\)

\(\dfrac{1}{4^2}< \dfrac{1}{3.4}\)

\(\dfrac{1}{5^2}< \dfrac{1}{4.5}\)

...

\(\dfrac{1}{100^2}< \dfrac{1}{99.100}\)

=>P<\(\dfrac{1}{1.2}+\dfrac{1}{2.3}+\dfrac{1}{3.4}+\dfrac{1}{4.5}+...+\dfrac{1}{99.100}\)

P<\(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+...+\dfrac{1}{99}-\dfrac{1}{100}\)

P<\(1-\dfrac{1}{100}\)

P<\(\dfrac{99}{100}\)

vì\(\dfrac{99}{100}< 1\)

=> P<1

vậy P<1