Tìm trong thực tế các hình ảnh gợi về:
a) Hai đường thẳng song song;
b) Hai đường thẳng cắt nhau.
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Bài `1`:
`a.` Rút gọn:
`21/35 = (21 : 7)/(35 : 7) = 3/5`
`=> BCNN(5,-25) = 25`.
`=> 3/5 = (3 * 5)/(5 * 5) = 15/25`
`=> 13/-25 = (13 * (-1) )/( (-25) * (-1) ) = (-13)/25`
`b.` `BCNN(5,-12,6) = 60.`
`=>` `2/5 = (2 * 12)/(5 * 12) = 24/60.`
`=>` `3/-12 = (3 * (-5) )/( (-12) * (-5) ) = (-15)/60`
`=>` `5/6 = (5 * 10)/(6 * 10) = 50/60`
Lời giải:
$\frac{1}{4^2}+\frac{1}{5^2}+\frac{1}{6^2}+...+\frac{1}{100^2}$
$< \frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+...+\frac{1}{99.100}$
$=\frac{4-3}{3.4}+\frac{5-4}{4.5}+\frac{6-5}{5.6}+...+\frac{100-99}{99.100}$
$=\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+...+\frac{1}{99}-\frac{1}{100}$
$=\frac{1}{3}-\frac{1}{100}< \frac{1}{3}$
Bài 2
a) x/(-3) = 4/7
x = 4/7 . (-3)
x = -12/7
b) -12/(-15) = x/25
x = 4/5 . 25
x = 20
c) (12 - x)/27 = 5/4
12 - x = 5/4 . 27
12 - x = 135/4
x = 12 - 135/4
x = -87/4
d) 12/(-3 - x) = 4/7
-3 - x = 12 : 4/7
-3 - x = 21
x = -3 - 21
x = -24
Bài 1
a) 21/35 = 3/5 = 15/25
13/(-25) = -13/25
b) 2/5 = 24/60
3/(-12) = -15/60
5/6 = 50/60
Ta có:
\(\dfrac{1}{2^2}< \dfrac{1}{1\cdot2}\)
\(\dfrac{1}{3^2}< \dfrac{1}{2\cdot3}\)
...
\(\dfrac{1}{2023^2}< \dfrac{1}{2022\cdot2023}\)
\(\Rightarrow\dfrac{1}{2^2}+\dfrac{1}{3^2}+...+\dfrac{1}{2023^2}< \dfrac{1}{1\cdot2}+\dfrac{1}{2\cdot3}+...+\dfrac{1}{2022\cdot2023}\)
\(\Rightarrow\dfrac{1}{2^2}+\dfrac{1}{3^2}+...+\dfrac{1}{2023^2}< 1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{2022}-\dfrac{1}{2023}\)
\(\Rightarrow\dfrac{1}{2^2}+\dfrac{1}{3^2}+...+\dfrac{1}{2023^2}< 1-\dfrac{1}{2023}< 1\)
\(13\cdot28-13\cdot12+16\cdot7\)
\(=13\left(28-12\right)+16\cdot7\)
\(=13\cdot16+16\cdot7=16\left(13+7\right)=16\cdot20=320\)
A = \(\dfrac{1}{7}\) + \(\dfrac{1}{7^2}\) + \(\dfrac{1}{7^3}\) + ... + \(\dfrac{1}{7^{100}}\)
7A = 7 + \(\dfrac{1}{7}\) + \(\dfrac{1}{7^2}\) + ....+ \(\dfrac{1}{7^{100}}\)
7A - A = (7 + \(\dfrac{1}{7}\) + \(\dfrac{1}{7^2}\) +... + \(\dfrac{1}{7^{99}}\)) - (\(\dfrac{1}{7}\) + \(\dfrac{1}{7^2}\) + \(\dfrac{1}{7^3}\) + ... + \(\dfrac{1}{7^{100}}\))
6A = 7 + \(\dfrac{1}{7}\) + \(\dfrac{1}{7^2}\) + ... + \(\dfrac{1}{7^{99}}\) - \(\dfrac{1}{7}\) - \(\dfrac{1}{7^2}\) - \(\dfrac{1}{7^3}\) - ... - \(\dfrac{1}{7^{100}}\)
6A = (\(\dfrac{1}{7}\) - \(\dfrac{1}{7}\)) + (\(\dfrac{1}{7^2}\) - \(\dfrac{1}{7^2}\)) + (\(\dfrac{1}{7^3}\) - \(\dfrac{1}{7^3}\)) +...+(\(\dfrac{1}{7^{99}}\) - \(\dfrac{1}{7^{99}}\))+ (7 - \(\dfrac{1}{7^{100}}\))
6A = 0 + 0 + ... + 0 + 7 - \(\dfrac{1}{7^{100}}\)
6A = 7 - \(\dfrac{1}{7^{100}}\)
A = (7 - \(\dfrac{1}{7^{100}}\)) : 6
A = \(\dfrac{7}{6}\) - \(\dfrac{1}{6.7^{100}}\)
G = \(\dfrac{3}{5}\) + \(\dfrac{3}{5^4}\) + \(\dfrac{3}{5^7}\) + ... + \(\dfrac{3}{5^{100}}\)
53G = 75 + \(\dfrac{3}{5}\) + \(\dfrac{3}{5^4}\) +... + \(\dfrac{3}{5^{99}}\)
125G - G = (75 + \(\dfrac{3}{5}\) + \(\dfrac{3}{5^4}\) + \(\dfrac{3}{5^7}\) + ... + \(\dfrac{3}{5^{99}}\)) - (\(\dfrac{3}{5}\) + \(\dfrac{3}{5^4}\)+\(\dfrac{3}{5^7}\)+...+\(\dfrac{3}{5^{100}}\))
124G = 75 + \(\dfrac{3}{5}\) + \(\dfrac{3}{5^4}\) + \(\dfrac{3}{5^7}\)+...+ \(\dfrac{3}{5^{99}}\) - \(\dfrac{3}{5}\) - \(\dfrac{3}{5^4}\) - \(\dfrac{3}{5^7}\) - ... - \(\dfrac{3}{5^{100}}\)
124G = (75 - \(\dfrac{3}{5^{100}}\)) + (\(\dfrac{3}{5}\) - \(\dfrac{3}{5}\)) +(\(\dfrac{3}{5^4}\) - \(\dfrac{3}{5^4}\)) +...+ (\(\dfrac{3}{5^{99}}\) - \(\dfrac{3}{5^{99}}\))
124G = 75 - \(\dfrac{3}{5^{100}}\) + 0 + 0 + ... + 0
124G = 75 - \(\dfrac{3}{5^{100}}\)
G = (75 - \(\dfrac{3}{5^{100}}\)): 124
G = \(\dfrac{75}{124}\) - \(\dfrac{3}{124.5^{100}}\)
Lời giải:
\(2022A=\frac{2022^{2024}+2022}{2022^{2024}+1}=1+\frac{2021}{2022^{2024}+1}< 1+\frac{2021}{2022^{2023}+1}=\frac{2022^{2023}+2022}{2022^{2023}+1}=2022B\)
$\Rightarrow A< B$
sossssssssssssssssssssss
cái này là nói hay tìm hình ảnh xong gửi cho giáo viên vậy bạn?