Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
a) ta co:
1/18<x/12<y/9<1/4
=>2/36<x.3/36<y.4/36<9/36
=>x.3thuộc{3;6};y.4thuộc{4;8}
=>x thuộc{1;2};y thuộc{1:2}
b) ta co
7/8<x/40<9/10
=>70/80<x.2/40<72/80
=>x.2 =71
=>x=71/2
\(\frac{x}{5}=\frac23\)
\(x\) = \(\frac23\times5\)
\(x=\frac{10}{3}\)
Vậy \(x=\frac{10}{3}\)
\(\frac{x}{3}-\frac12=\frac15\)
\(\frac{x}{3}\) = \(\frac15\) + \(\frac12\)
\(\frac{x}{3}\) = \(\frac{2}{10}+\frac{5}{10}\)
\(\frac{x}{3}=\frac{7}{10}\)
\(x=\frac{7}{10}\times3\)
\(x=\frac{21}{10}\)
Vậy \(x=\frac{21}{10}\)
\(\frac{x}{5}+\frac12=\frac{6}{10}\)
\(\frac{x}{5}=\frac{6}{10}-\frac12\)
\(\frac{x}{5}=\frac{6}{10}-\frac{5}{10}\)
\(\frac{x}{5}=\frac{1}{10}\)
\(x=\frac{1}{10}\times5\)
\(x=\frac12\)
Vậy \(x=\frac12\)
\(\frac{x+3}{15}\) = \(\frac13\)
\(x+3=\frac13\times15\)
\(x+3=5\)
\(x=5-3\)
\(x=2\)
Vậy \(x=2\)
a)2A=1+1/2^1+1/2^2+...+1/2^98
2A-A=1+1/2^1+1/2^2+...+1/2^98-(1/2^1+1/2^2+...+1/2^99)
A=1+1/2^1+1/2^2+...+1/2^98-1/2^1-1/2^2-...-1/2^99
A=1-1/2^99
tìm x a)
\(\dfrac{7}{2}\)-\(\left(x+\dfrac{7}{10}\right)\): \(\dfrac{6}{5}\) = \(\dfrac{-5}{4}\)
\(\left(x+\dfrac{7}{10}\right)\): \(\dfrac{6}{5}\) = \(\dfrac{-5}{4}\) + \(\dfrac{7}{2}\)
\(\left(x+\dfrac{7}{10}\right)\): \(\dfrac{6}{5}\) = \(\dfrac{-5}{12}+\dfrac{7}{12}\)
\(\left(x+\dfrac{7}{10}\right)\): \(\dfrac{6}{5}\) = \(\dfrac{-12}{12}=1\)
\(x+\dfrac{7}{10}\)= 1 . \(\dfrac{6}{5}\)
*Rồi tự làm phần tt đi
Ta có:
\(37 - 5 \left(\right. x + 9 \left.\right) = \mid - 17 \mid\)
👉 Vì \(\mid - 17 \mid = 17\)
⇒ \(37 - 5 \left(\right. x + 9 \left.\right) = 17\)
\(37 - 5 x - 45 = 17\) \(- 5 x - 8 = 17\) \(- 5 x = 25 \Rightarrow x = - 5\)
✅ Đáp án: x = -5
b)
\(- 2 < \mid x + 2 \mid < 2\)
👉 Vì \(\mid x + 2 \mid \geq 0\) nên điều kiện \(- 2 < \mid x + 2 \mid\) luôn đúng
⇒ chỉ cần:
\(\mid x + 2 \mid < 2\) \(- 2 < x + 2 < 2\) \(- 4 < x < 0\)
✅ Đáp án: \(- 4 < x < 0\)
c)
\(- 7 \mid x - 2013 \mid + 20120 = \mid + 1 \mid\)
👉 \(\mid + 1 \mid = 1\)
⇒
\(- 7 \mid x - 2013 \mid + 20120 = 1\) \(- 7 \mid x - 2013 \mid = 1 - 20120 = - 20119\) \(\mid x - 2013 \mid = \frac{20119}{7} = 2874.142857...\)
⇒
\(x - 2013 = \pm \frac{20119}{7}\) \(x = 2013 \pm \frac{20119}{7}\)
👉 Có 2 nghiệm:
- \(x = 2013 + \frac{20119}{7}\)
- \(x = 2013 - \frac{20119}{7}\)
(= khoảng 4887.14 và -861.14)
d)
\(21 + \left(\right. x - 10 \left.\right) = - 19\)
\(21 + x - 10 = - 19\) \(x + 11 = - 19\) \(x = - 30\)
✅ Đáp án: x = -30
✅ Tóm lại:
- a) \(x = - 5\)
- b) \(- 4 < x < 0\)
- c) \(x = 2013 \pm \frac{20119}{7}\)
- d) \(x = - 30\)
92=81
132=169
k mình nhé!
\(9^2=81\) \(13^2=169\)
k mk nha mina~~~~~~~~~~
sđfghj
\(9^2\)\(=9.9\)
\(=81\)
\(13^2\)\(=13.13\)
\(=169\)
92=9x9=81
132=13x13=169
Chúc bạn học tốt!
81
169