x+10+90=120
x=?
K
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9 tháng 3 2020
5x2-120x-125=0
x(5x-120)=0+125
x(5x-120)=125
\(\Rightarrow\orbr{\begin{cases}x=125\\5x-120=125\Rightarrow5x=125-120\Rightarrow5x=5\Rightarrow x=5:5=1\end{cases}}\)
Vậy x=125 hoặc x=1
9 tháng 3 2020
\(5x^2-120x-125=0\)
\(5\left(x^2-24x-25\right)=0\)
\(5\left(x-25\right)\left(x+1\right)=0\)
\(\Rightarrow5=0\)vô nghiệm
\(\Rightarrow\orbr{\begin{cases}x-25=0\\x+1=0\end{cases}\Rightarrow\orbr{\begin{cases}x=25\\x=-1\end{cases}}}\)
29 tháng 6 2022
\(x=\dfrac{\left(\dfrac{18}{60}-\dfrac{16}{60}-\dfrac{21}{60}\right)\cdot\dfrac{5}{19}}{\left(\dfrac{5}{70}+\dfrac{10}{70}+\dfrac{6}{70}\right)\cdot\dfrac{-4}{3}}\)
\(=\dfrac{\dfrac{-19}{60}\cdot\dfrac{5}{19}}{\dfrac{3}{10}\cdot\dfrac{-4}{3}}=\dfrac{-5}{60}:\dfrac{-4}{10}=\dfrac{1}{12}\cdot\dfrac{5}{2}=\dfrac{5}{24}\)
Khi x=5/24 thì \(P=\sqrt{120\cdot\dfrac{5}{24}+39}=\sqrt{25+39}=8\)
AD
1
21 tháng 1
\(\dfrac{20x^2+120x+180}{\left(3x+5\right)^2-4x^2}+\dfrac{5x^2-25}{9x^2-\left(2x+5\right)^2}-\dfrac{\left(2x+3\right)^2-x^2}{3\left(x^2+8x+15\right)}\)
\(=\dfrac{20\left(x^2+6x+9\right)}{\left(3x+5+2x\right)\left(3x+5-2x\right)}+\dfrac{5\left(x-5\right)\left(x+5\right)}{\left(3x-2x-5\right)\left(3x+2x+5\right)}-\dfrac{\left(2x+3-x\right)\left(2x+3+x\right)}{3\left(x+3\right)\left(x+5\right)}\)
\(=\dfrac{20\left(x+3\right)^2}{5\left(x+1\right)\cdot\left(x+5\right)}+\dfrac{5\left(x-5\right)\left(x+5\right)}{5\left(x+1\right)\left(x-5\right)}-\dfrac{\left(x+3\right)\cdot3\left(x+1\right)}{3\left(x+3\right)\left(x+5\right)}\)
\(=\dfrac{4\left(x+3\right)^2}{\left(x+1\right)\left(x+5\right)}+\dfrac{x+5}{x+1}-\dfrac{x+1}{x+5}\)
\(=\dfrac{4\left(x+3\right)^2+\left(x+5\right)^2-\left(x+1\right)^2}{\left(x+1\right)\left(x+5\right)}\)
\(=\dfrac{4x^2+24x+36+x^2+10x+25-x^2-2x-1}{\left(x+1\right)\cdot\left(x+5\right)}\)
\(=\dfrac{4x^2+32x+60}{\left(x+1\right)\left(x+5\right)}=\dfrac{4\left(x^2+8x+15\right)}{\left(x+1\right)\left(x+5\right)}\)
\(=\dfrac{4\left(x+3\right)\cdot\left(x+5\right)}{\left(x+1\right)\left(x+5\right)}=\dfrac{4x+12}{x+1}\)
DN
3
10 tháng 3 2022
120 x 5/6
= 600/6 = 100/1 = 100
5/6 x 76
= 380/6 = 190/3
17 tháng 9 2017
a) \(\left(314-x\right)-42=0\)
\(314-x=42\)
\(x=272\)
vay \(x=272\)
b) \(540+\left(345-x\right)=740\)
\(345-x=200\)
\(x=145\)
vay \(x=145\)
c) \(\left(x-72\right):36=418\)
\(x-72=15048\)
\(x=15120\)
vay \(x=15120\)
d) \(2010\left(x-14\right)=0\)
\(x-14=0\)
\(x=14\)
vay \(x=14\)
e) \(\left(x-2\right)\left(x-4\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x-2=0\\x-4=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=2\\x=4\end{cases}}\)
vay \(\orbr{\begin{cases}x=2\\x=4\end{cases}}\)
f) \(114-\left(x-47\right)=0\)
\(x-47=114\)
\(x=161\)
vay \(x=161\)
g) \(7272:\left(120x-91\right)=12\)
\(120x-91=606\)
\(120x=697\)
\(x=\frac{697}{120}\)
vay \(x=\frac{697}{120}\)
5 tháng 8 2018
Despacito đã có dấu'' x= '' thì ko cần kết luận là '' vậy''
22 tháng 7 2023
Khi x=100 thì \(C=\dfrac{0.0002\cdot100^2+120\cdot100+1000}{100}=\dfrac{6501}{50}\)
Khi x=1000 thì \(C=\dfrac{0.0002\cdot1000^2+120\cdot1000+1000}{1000}=\dfrac{606}{5}\)
H9
HT.Phong (9A5)
CTVHS
19 tháng 8 2023
\(\left(84,6-2\cdot x\right):3,02=5,1\)
\(\Rightarrow84,6-2\cdot x=15,402\)
\(\Rightarrow2\cdot x=69,198\)
\(\Rightarrow x=69,198:2\)
\(\Rightarrow x=34,599\)
_____________
\(\left(15\cdot24-x\right):0,25=100:0,25\)
\(\Rightarrow\left(360-x\right):0,25=400\)
\(\Rightarrow360-x=100\)
\(\Rightarrow x-360-100\)
\(\Rightarrow x=260\)
______________
\(128\cdot x-12\cdot x-16\cdot x=5200\)
\(\Rightarrow x\cdot\left(128-12-16\right)=5200\)
\(\Rightarrow x\cdot100=5200\)
\(\Rightarrow x=5200:100\)
\(\Rightarrow x=52\)
__________________
\(5\cdot x+3,75\cdot x+1,25\cdot x=20\)
\(\Rightarrow x\cdot\left(5+3,75+1,25\right)=20\)
\(\Rightarrow10\cdot x=20\)
\(\Rightarrow x=20:10\)
\(\Rightarrow x=2\)
H9
HT.Phong (9A5)
CTVHS
19 tháng 8 2023
\(x\cdot3,7+x\cdot6,3=360:120\)
\(\Rightarrow x\cdot\left(3,7+6,3\right)=3\)
\(\Rightarrow x\cdot10=3\)
\(\Rightarrow x=\dfrac{3}{10}\)
__________________
\(x\cdot23-6\cdot23+x\cdot69=320\)
\(\Rightarrow x\cdot\left(23+69\right)=320+6\cdot23\)
\(\Rightarrow x\cdot92=458\)
\(\Rightarrow x=458:92\)
\(\Rightarrow x=\dfrac{229}{46}\)
___________________
\(\left(x+1\right)\left(x+2\right)=72\)
\(\Rightarrow x^2+2x+x+2=72\)
\(\Rightarrow x^2+3x+2=72\)
\(\Rightarrow x^2+3x+2-72=0\)
\(\Rightarrow x^2+3x-70=0\)
\(\Rightarrow x^2+10x-7x-70=0\)
\(\Rightarrow\left(x-7\right)\left(x+10\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=7\\x=-10\end{matrix}\right.\)
___________________
\(\left(x+2\right)\cdot16\cdot x=160x\)
\(\Rightarrow16x^2+32x=160x\)
\(\Rightarrow16x^2+32x-160x=0\)
\(\Rightarrow16x^2-128x=0\)
\(\Rightarrow16x\left(x-8\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=0\\x=8\end{matrix}\right.\)
KN
23 tháng 11 2019
\(A=x^2+3x-5=x^2+3x+\frac{9}{4}-\frac{29}{4}\)
\(=\left(x+\frac{3}{2}\right)^2-\frac{29}{4}\ge-\frac{29}{4}\)
Vậy \(A_{min}=-\frac{29}{4}\Leftrightarrow x+\frac{3}{2}=0\Leftrightarrow x=-\frac{3}{2}\)
=100 nhe kb nhe
=20
ai tk mk, mk tk lại