75%x - 1/2x = 2,5
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a) 0,01 : 25 = ( 0,75 . x ) : 0,75
\(\Rightarrow\frac{1}{2500}=0,75\cdot x:0,75\)
\(\Rightarrow x=\frac{1}{2500}\)
b) \(\left(3,8\right):\left(2x\right)=\frac{1}{4}:\frac{8}{3}\)
\(\Rightarrow3,8:\left(2x\right)=\frac{3}{32}\)
\(\Rightarrow2x=3,8:\frac{3}{32}=\frac{608}{15}\)
\(\Rightarrow x=\frac{608}{15}:2=\frac{304}{15}\)
(2,5 x 11,25 + 11,25 x 7,5) x( 75 x 11 - 75 : 0,1 - 75)
ai nhanh tớ sẽ tick ạ, ghi đầy đủ lời giải ạ= ( 11,25 x (2,5 + 7,5) ) x ( 75 x 11 - 75 : 0,1 -75 x1)
=( 11,25 x 10) x (75 x ( 11 -1 :0,1 ) )
= 112,5 x ( 75 x 100 )
= 112,5 x 7500
= 1125000
( 2,5 \(\times\) 11,25 \(\) + 11,25 \(\times\)7,5) \(\times\)( 75 \(\times\) 11 - 75: 0,1 - 75)
= (2,5 \(\times\) 11,25 + 11,25 \(\times\) 7,5) \(\times\)( 75 \(\times\) 11 - 75 \(\times\) 10 - 75 \(\times\) 1)
=( 2,5 \(\times\) 11,25 + 11,25 \(\times\) 7,5) \(\times\) 75 \(\times\)( 11 - 10 - 1)
= ( 2,5 \(\times\) 11,25 + 11,25 \(\times\)7,5 ) \(\times\) 75 \(\times\) 0
= 0
tìm x , biết :
a . 1,5 . x + 2,5 = 1
\(1,5.x=-1,5\)
\(x=\dfrac{-1,5}{1,5}\)
\(x=-1\)
b . ( 0,5 . x - 1,3 ) : 0,5 = -1,7
\(0,5.x-1,3=-0,85\)
\(0,5x=-2,15\)
\(x=\dfrac{-2,15}{0,5}\)
\(x=-4,3\)
c . 1,75 .x - 1,5 . x = 0,84
\(x\left(1,75-1,5\right)=0,84\)
\(x.0,25=0,84\)
\(x=3,36\)
d . x + 75% . x + 125% = 1
\(x+\dfrac{75}{100}.x+\dfrac{125}{100}=1\)
\(x+\dfrac{3}{4}.x+\dfrac{5}{4}=1\)
\(x+\dfrac{3}{4}.x=-\dfrac{1}{4}\)
\(x.\left(1+\dfrac{3}{4}\right)=-\dfrac{1}{4}\)
\(x.1,75=-\dfrac{1}{4}\)
\(x=-\dfrac{1}{7}\)
e . x - 25% .x + 75% = 1
\(x-\dfrac{25}{100}.x+\dfrac{75}{100}=1\)
\(x-\dfrac{1}{4}.x+\dfrac{3}{4}=1\)
\(x-\dfrac{1}{4}.x=\dfrac{1}{4}\)
\(x.\left(1-\dfrac{1}{4}\right)=\dfrac{1}{4}\)
\(x.\dfrac{3}{4}=\dfrac{1}{4}\)
\(x=\dfrac{1}{3}\)
f . | x - 1,5 | = 2,37
TH1 : \(x-1,5=2,37\)
\(x=2,37+1,5\)
\(x=3,87\)
TH2 : \(x-1,5=-2,37\)
\(x=-2,37+1,5\)
\(x=-0,87\)
a: \(\Leftrightarrow\left(x-\dfrac{2}{5}\right):\dfrac{3}{2}=-\dfrac{5}{4}+\dfrac{5}{2}=\dfrac{5}{4}\)
\(\Leftrightarrow x-\dfrac{2}{5}=\dfrac{5}{4}\cdot\dfrac{3}{2}=\dfrac{15}{8}\)
hay x=91/40
b: \(\Leftrightarrow\left(2.5x-3.6\right)=-1\cdot\dfrac{12}{7}=\dfrac{-12}{7}\)
=>2,5x=66/35
hay x=132/175
c: \(\Leftrightarrow\left(\dfrac{15}{4}-2x\right)=\dfrac{19}{9}:\dfrac{4}{3}=\dfrac{19}{9}\cdot\dfrac{3}{4}=\dfrac{19}{12}\)
=>2x=15/4-19/12=45/12-19/12=26/12
=>x=13/12
\(\Leftrightarrow x^2+2x-3,5=0\\ \Leftrightarrow2x^2+4x-7=0\\ \Leftrightarrow2\left(x^2+2x+1\right)-9=0\\ \Leftrightarrow2\left[\left(x+1\right)^2-\dfrac{9}{2}\right]=0\\ \Leftrightarrow\left(x+1-\dfrac{3}{\sqrt{2}}\right)\left(x+1+\dfrac{3}{\sqrt{2}}\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=\dfrac{3}{\sqrt{2}}-1=\dfrac{3-\sqrt{2}}{\sqrt{2}}\\x=\dfrac{3}{\sqrt{2}}+1=\dfrac{3+\sqrt{2}}{\sqrt{2}}\end{matrix}\right.\)
đơn giản thôi bạn
3 (x + 25)
= 3x + 3*25 (bạn nhân 3 với từng số trong ngoặc) (*là nhân nhé)
= 3x + 75
=> 3/4.x - 1/2.x = 2,5
=> 1/4.x = 2,5
=> x = 2,5 : 1/4
=> x = 2,5 . 4
=> x = 10
dấu .=x ( nhân )
3/4x-1/2x=5/2
x.(3/4-1/2)=5/2
x.1/4=5/2
x=5/2:1/4
x=5/2.4/1
x=10/1
đúng thì tích nha