3/2x-(4/5-2x)=13/10. (Giúp mik với,27/6 thi rồi)
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25 tháng 6 2019
\(A=\frac{1}{2^2}+\cdot\cdot\cdot+\frac{1}{2018^2}\)<\(\frac{1}{1\cdot2}+\cdot\cdot\cdot+\frac{1}{2017\cdot2018}\)
\(\Rightarrow A\)<\(1-\frac{1}{2}+\cdot\cdot\cdot+\frac{1}{2017}-\frac{1}{2018}\)
\(\Rightarrow A\)<\(1-\frac{1}{2018}\)<\(1\)
LK
1
6 tháng 9 2021
\(\frac{2x-10}{6}=\frac{-27}{5-x}\)
\(\frac{2\left(x-5\right)}{6}=\frac{27}{x-5}\)
\(2\left(x-5\right)^2=27\times6\)
\(2x^2-20x+50-162=0\)
\(2x^2-20x-112=0\)
\(x^2-10x-56=0\)
\(x^2-14x+4x-56=0\)
\(\left(x-14\right)\left(x+4\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x-14=0\\x+4=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=14\\x=-4\end{cases}}\)
KL .....
XIN TIICK
4 tháng 8 2017
Ta có : 6x2 - 11x + 3
= 6x2 - 2x - 9x + 3
= (6x2 - 2x) - (9x - 3)
= 2x(3x - 1) - 3(3x - 1)
= (2x - 3)(3x - 1)
NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
25 tháng 7
a; \(\dfrac{2}{3}\)\(x\) - \(\dfrac{3}{2}\)\(x\) = \(\dfrac{5}{12}\)
(\(\dfrac{2}{3}\) - \(\dfrac{3}{2}\))\(x\) = \(\dfrac{5}{12}\)
- \(\dfrac{5}{6}\)\(x\) = \(\dfrac{5}{12}\)
\(x\) = \(\dfrac{5}{12}\) : (- \(\dfrac{5}{6}\))
\(x=\) - \(\dfrac{1}{2}\)
Vậy \(x=-\dfrac{1}{2}\)
NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
25 tháng 7
b; \(\dfrac{2}{5}\) + \(\dfrac{3}{5}\).(3\(x\) - 3,7) = \(\dfrac{-53}{10}\)
\(\dfrac{3}{5}\).(3\(x\) - 3,7) = \(\dfrac{-53}{10}\) - \(\dfrac{2}{5}\)
\(\dfrac{3}{5}\).(3\(x\) - 3,7) = - \(\dfrac{57}{10}\)
3\(x\) - 3,7 = - \(\dfrac{57}{10}\) : \(\dfrac{3}{5}\)
3\(x\) - 3,7 = - \(\dfrac{19}{2}\)
3\(x\) = - \(\dfrac{19}{2}\) + 3,7
3\(x\) = - \(\dfrac{29}{5}\)
\(x\) = - \(\dfrac{29}{5}\) : 3
\(x\) = - \(\dfrac{29}{15}\)
Vậy \(x\) \(\in\) - \(\dfrac{29}{15}\)
NT
1
14 tháng 8 2016
\(\frac{2x}{4}:-5=\frac{1}{7}\)
\(\frac{x}{2}=-\frac{5}{7}\)
\(x=-\frac{10}{7}\)
PT
3
LC
25 tháng 9 2018
a,\(\left(x-1\right)^2=4=2^2=\left(-2\right)^2\)
\(\Rightarrow\orbr{\begin{cases}x-1=2\\x-1=-2\end{cases}\Rightarrow\orbr{\begin{cases}x=3\\x=-1\end{cases}}}\)
b,\(\left(2x+1\right)^3=27=3^3\)
\(\Rightarrow2x+1=3\Rightarrow x=1\)
c,\(\left(2x-1\right)^5=x^5\Rightarrow2x-1=x\Rightarrow x=1\)
25 tháng 9 2018
\(a,\left(x-1\right)^2=4\)
\(\Rightarrow x-1=2\)
\(\Rightarrow x=3\)
\(b,\left(2x+1\right)^3=27\)
\(\Rightarrow2x+1=3\)
\(\Rightarrow x=1\)
\(c,\left(2x-1\right)^5=x^5\)
\(\Rightarrow2x-1=x\)
\(\Rightarrow2x-x-1=0\)
\(\Rightarrow x=1\)
Học tốt!
27 tháng 8 2021
\(\dfrac{5}{x}+1+\dfrac{4}{x}+1=\dfrac{3}{-13}\\ \Rightarrow\dfrac{9}{x}+2=-\dfrac{3}{13}\\ \Rightarrow\dfrac{9}{x}=-\dfrac{59}{13}\\ \Rightarrow x=-\dfrac{207}{59}\)
KK
27 tháng 8 2021
a. \(\dfrac{5}{x+1}+\dfrac{4}{x+1}=\dfrac{-3}{13}\)
ĐKXĐ: x ≠ -1
⇔ \(\dfrac{65}{13\left(x+1\right)}+\dfrac{52}{13\left(x+1\right)}=\dfrac{-3\left(x+1\right)}{13\left(x+1\right)}\)
⇔ 65 + 52 = -3(x + 1)
⇔ 117 = -3x - 3
⇔ 117 + 3 = -3x
⇔ 120 = -3x
⇔ x = \(\dfrac{120}{-3}=-40\) (TM)
b. -x + 2 + 2x + 3 + x + \(\dfrac{1}{4}\) + 2x + \(\dfrac{1}{6}\) = \(\dfrac{8}{3}\)
⇔ -x + 2x + x + 2x = \(\dfrac{8}{3}-\dfrac{1}{6}-\dfrac{1}{4}-3-2\)
⇔ 4x = -2,75
⇔ x = \(\dfrac{-2,75}{4}=\dfrac{-11}{16}\)
c. \(\dfrac{3}{2x+1}+\dfrac{10}{4x+2}-\dfrac{6}{6x+2}\) = \(\dfrac{12}{26}\)
⇔ \(\dfrac{3}{2x+1}+\dfrac{10}{2\left(2x+1\right)}-\dfrac{6}{2\left(3x+1\right)}=\dfrac{12}{26}\)
⇔ \(\dfrac{312\left(3x+1\right)}{104\left(2x+1\right)\left(3x+1\right)}\) + \(\dfrac{520\left(3x+1\right)}{104\left(2x+1\right)\left(3x+1\right)}\) - \(\dfrac{312\left(2x+1\right)}{104\left(2x+1\right)\left(3x+1\right)}\)
= \(\dfrac{48\left(2x+1\right)\left(3x+1\right)}{104\left(2x+1\right)\left(3x+1\right)}\)
⇔ 312(3x +1) + 520(3x + 1) - 312(2x + 1) = 48(2x + 1)(3x + 1)
⇔ 936x + 312 + 1560x + 520 - 624x - 312 = (96x + 48)(3x + 1)
⇔ 936x + 312 + 1560x + 520 - 624x - 312 = 288x2 + 96x + 144x + 48
⇔ 936x + 1560x - 624x - 96x - 144x - 288x2 = 48 - 312 - 520 + 312
⇔ 1632x - 288x2 = -472
⇔ -288x2 + 1632x + 472 = 0 (Tự giải tiếp, dùng phương pháp tách hạng tử)
⇔ x = 5,942459684 \(\approx\) 6
\(\frac{3}{2}x-\left(\frac{4}{5}-2\text{x}\right)=\frac{13}{10}\)
\(\Leftrightarrow\frac{3}{2}x-\frac{4}{5}+2\text{x}=\frac{13}{10}\)
\(\Leftrightarrow\frac{3}{2}x+2\text{x}=\frac{13}{10}+\frac{4}{5}\)
\(\Leftrightarrow\frac{3\text{x}+4\text{x}}{2}=\frac{13}{10}+\frac{8}{10}\)
\(\Leftrightarrow\frac{7}{2}x=\frac{21}{10}\)
\(\Leftrightarrow x=\frac{21}{10}\div\frac{7}{2}=\frac{21}{10}\cdot\frac{2}{7}=\frac{3}{5}\)
Vậy x = \(\frac{3}{5}\)
3/5 nha
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