mn giúp mik nha! thanks
X x 1/4 + X x 75% = 20,23 x 90 + 202,3
K
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19 tháng 9 2018
7(x - 3) - x(3 - x)
= (x - 3)(7 + x)
chỉ bt có v mà k bt có đúng k
SM
19 tháng 9 2018
1 ) 7 ( x - 3 ) - x ( 3 - x )
= 7 ( x - 3 ) + x ( x - 3 )
= ( x - 3 ) ( 7 + x )
2 ) 4x2 - 6x + 3 - 2x
= 4x2 - 2x - 6x + 3
= 2x ( 2x - 1 ) - 3 ( 2x - 1 )
= ( 2x - 1 ) ( 2x - 3 )
3 ) ( 4 - x ) - 4x + x2
= ( 4 - x ) - x ( 4 - x )
= ( 4 - x ) ( 1 - x )
4 ) x2 - 2xy + y2
= ( x - y )2
K
1
30 tháng 12 2021
\(=2.34\left(2+2\cdot2+3\cdot2-2\right)=2.34\cdot10=23.4\)
NL
1
17 tháng 1 2023
\(0,18\text{×}1230+0,9\text{×}1567\text{×}2-3\text{×}690\\ =221,4+2820,6-2070=1015\)
NT
0
T
29 tháng 8 2018
\(284:\left[314-\left(x+3\right)\right]=12.\)
\(\Leftrightarrow\left[314-\left(x+3\right)\right]=\frac{71}{3}\)
\(\Leftrightarrow\left(x+3\right)=\frac{871}{3}\)
\(\Leftrightarrow x=\frac{862}{3}\)
\(14.\left[251-\left(x-5\right)\right]=1470\)
\(\Leftrightarrow\left[251-\left(x-5\right)\right]=105\)
\(\Leftrightarrow x-5=146\)
\(\Leftrightarrow x=151\)
\(\left(120+x\right):x-15=16\)
\(\Leftrightarrow\left(120+x\right):x=31\)
\(\Leftrightarrow\left(120+x\right).\frac{1}{x}=31\)
\(\Leftrightarrow\frac{1}{x}.x+120x=31\)
\(\Leftrightarrow1+120x=31\)
\(\Leftrightarrow120x=30\)
\(\Leftrightarrow x=4\)
\(\left(135-x\right):x+24=28\)
\(\Leftrightarrow\left(135-x\right):x=4\)
\(\Leftrightarrow\left(135-x\right).\frac{1}{x}=4\)
\(\Leftrightarrow\frac{1}{x}.135-\frac{1}{x}x=4\)
\(\Leftrightarrow\frac{1}{x}135-1=4\)
\(\Leftrightarrow\frac{1}{x}135=5\)
\(\Leftrightarrow\frac{1}{x}=\frac{1}{27}\)
\(\Leftrightarrow x=27\)
25 tháng 9 2017
a) |x| + |x-2| = 2
TH1: \(x< 0\Rightarrow-x-x+2=2\Leftrightarrow-2x=0\Rightarrow x=0\)
TH2: \(0\le x< 2\Rightarrow x-x+2=0\Rightarrow0x=-2\)(PT vô nghiệm)
TH3: \(x>2\Rightarrow x+x-2=0\Rightarrow2x=2\Rightarrow x=1\)(loại vì 1<2 không thỏa mãn ĐK)
b) |x-1| + |x-4| = 3x
TH1: \(x-1\le0\Rightarrow x\le1\)
\(-x+1-x+4=3x\Leftrightarrow5-2x=3x\Leftrightarrow5x=5\Rightarrow x=1\)
TH2: \(1\le x\le4\)
\(x-1-x+4=3x\Leftrightarrow3x=3\Rightarrow x=1\)
TH3: \(x\ge4\)
\(x-1+x-4=3x\Leftrightarrow2x-5=3x\Rightarrow x=-5\)(loại vì -5<4 không thỏa mãn với ĐK)
LT
2
NH
2
2 tháng 1 2023
a: =20,23(15,75+85,25-1)
=20,23*100
=2023
b: =0,66+3,34+2,8+1,2
=4+4
=8
F
23 tháng 1 2020
Bài giải
\(\frac{1}{2}\left(x+1\right)+\frac{1}{4}\left(x+3\right)=3\cdot\frac{1}{3}\cdot\left(x+20\right)\)
\(\frac{1}{2}\left[\left(x+1\right)+\frac{1}{2}\left(x+3\right)\right]=x+20\)
\(\frac{1}{2}\left[x+1+\frac{1}{2}x+\frac{3}{2}\right]=x+20\)
\(\frac{1}{2}\left[x\left(1+\frac{1}{2}\right)+1+\frac{3}{2}\right]=x+20\)
\(\frac{1}{2}\left[\frac{3}{2}x+\frac{5}{2}\right]=x+20\)
\(\frac{3}{4}x+\frac{5}{4}=x+20\)
\(\frac{3}{4}x-x=20-\frac{5}{4}\)
\(\frac{-1}{4}x=\frac{75}{4}\)
\(x=\frac{75}{4}\text{ : }\frac{-1}{4}\)
\(x=-75\)
M
23 tháng 1 2020
\(\frac{1}{2}\left(x+1\right)+\frac{1}{4}\left(x+3\right)=3\cdot\frac{1}{3}\cdot\left(x+20\right)\)
\(\frac{1}{2}\left[\left(x+1\right)+\frac{1}{2}\left(x+3\right)\right]=x+20\)
\(\frac{1}{2}\left[x+1+\frac{1}{2}x+\frac{3}{2}\right]=x+20\)
\(\frac{1}{2}\left[x\left(1+\frac{1}{2}\right)+1+\frac{3}{2}\right]=x+20\)
\(\frac{1}{2}\left[\frac{3}{2}x+\frac{5}{2}\right]=x+20\)
\(\frac{3}{4}x+\frac{5}{4}=x+20\)
\(\frac{3}{4}x-x=20-\frac{5}{4}\)
\(\frac{-1}{4}x=\frac{75}{4}\)
\(x=\frac{75}{4}\text{ : }\frac{-1}{4}\)
\(x=-75\)
\(x\times\dfrac{1}{4}+x\times75\%=20,23\times90+202,3\)
\(x\times\dfrac{1}{4}+x\times\dfrac{3}{4}=20,23\times90+20,23\times10\)
\(x\times\left(\dfrac{1}{4}+\dfrac{3}{4}\right)=20,23\times\left(90+10\right)\)
\(x\times1=20,23\times100\)
\(x=2023\)
X x 1/4+ X x 75% = 20,23 x 90 +202,3
X x 1/4+ X x 3/4 = 2023
X x ( 1/4 +3/4 ) = 2023
X x 1 = 2023
x = 2023