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\(\frac{2}{5}.\frac{1}{x}+\frac{1}{x}.2+\frac{2}{5}=0,5\)
\(\Rightarrow\frac{2}{5x}+\frac{2}{x}+\frac{2}{5}=\frac{1}{2}\)
\(\Rightarrow2.\left(\frac{1}{5x}+\frac{1}{x}+\frac{1}{5}\right)=\frac{1}{2}\)
\(\Rightarrow\frac{1}{5x}+\frac{5}{5x}+\frac{x}{5x}=\frac{1}{2}:2=\frac{1}{4}\)
\(\Rightarrow\frac{1+5+x}{5x}=\frac{1}{4}\)
\(\Rightarrow4.\left(1+5+x\right)=5x\)
\(\Rightarrow4+20+4x=5x\)
\(\Rightarrow24+4x=5x\)
\(\Rightarrow5x-4x=24\)
\(\Rightarrow x=24\)
a) \(\left(x^2-9\right)\cdot\left(4^x-16\right)=0\)
\(\Rightarrow x^2-9=0\)hoặc \(4^x-16=0\)
\(x^2=9\) \(4^x=16\)
\(x^2=\left(\pm3\right)^2\) \(4^x=4^2\)
\(\Rightarrow x=\pm3\)hoặc \(x=2\)
b) \(5^x+5^{x+2}=650\)
\(\Rightarrow5^x+5^x\cdot25=650\)
\(\Rightarrow5^x\cdot\left(1+25\right)=650\)
\(\Rightarrow5^x\cdot26=650\)
\(\Rightarrow5^x=650\div26=25\)
\(\Rightarrow5^x=5^2\)
\(\Rightarrow x=2\)Vậy \(x=2\)
c) \(2^{x+2}-2^x=96\)
\(2^x\cdot4-2^x=96\)
\(2^x\cdot\left(4-1\right)=96\)
\(2^x\cdot3=96\)
\(2^x=96\div3=32\)
\(2^x=2^5\)Vậy \(x=5\)
* \(20+65.4=\left(x+75\right):5+30\)
\(\Leftrightarrow20+260-30=\frac{x}{5}+\frac{75}{5}\)
\(\Leftrightarrow20+260-30-\frac{75}{5}=\frac{x}{5}\)
\(\Leftrightarrow235=\frac{x}{5}\Rightarrow x=235.5=1175\)
* \(2248:\left[119-\left(x-6\right)\right]=24\)
\(\Leftrightarrow2248:\left(119-x+6\right)=24\)
\(\Leftrightarrow2248:\left(125-x\right)=24\)
A mình lỡ tay, để mình tính tiếp nhá!
\(\Leftrightarrow125-x=2248:24\Leftrightarrow125-x=\frac{281}{3}\Rightarrow-x=\frac{94}{3}\Rightarrow x=-\frac{94}{3}\)(bài này mình thấy sai sai sao á, nếu mình làm sai thì thông cảm cho mình nhé!
* \(\left(x+70\right):14-40=\left(32.15\right):2\)
\(\Leftrightarrow\left(x+70\right):14=480:2+40\)
\(\Leftrightarrow\frac{x}{14}+5=280\Leftrightarrow\frac{x}{14}=275\Rightarrow x=3850\)
* \(x-4867=\left(175.2050.70\right):25+23\)
\(\Leftrightarrow x-4867-23=\left(175:25\right).\left(2050:25\right).\left(70:25\right)\)
\(\Leftrightarrow x-4890=7.82.\frac{14}{5}\)
\(\Leftrightarrow x-4890=\frac{8036}{5}\Rightarrow x=\frac{8036}{5}+4890=\frac{32486}{5}\)(bài này mình thấy hình như cũng có cái gì đó sai sai luôn hihi!)
a) \(5+3^{x+1}=86\)
\(=>3^{x+1}=86-5\)
\(=>3^{x+1}=81=3^4\)
\(=>x+1=4\) ( cùng cơ số )
\(=>x=4-1\)
\(=>x=3\)
b) \(15:\left(x+2\right)=\left(3^3+3\right):10\)
\(=>15:\left(x+2\right)=\left(27+3\right):10\)
\(=>15:\left(x+2\right)=30:10=3\)
\(=>x+2=15:3\)
\(=>x+2=5\)
\(=>x=5-2\)
\(=>x=3\)
c) \(\left(9x+2\right).4=80\)
\(=>9x+2=80:4\)
\(=>9x+2=20\)
\(=>9x=20-2\)
\(=>9x=18\)
\(=>x=18:9\)
\(=>x=2\)
d) \(\left(245-x\right)+7^2=14\)
\(=>\left(245-x\right)+14=14\)
\(=>245-x=14-14\)
\(=>245-x=0\)
\(=>x=245-0\)
\(=>x=245\)
Bài 1 tìm x
A, (19..x+2..52)..14= (13-18)-42
B, 2..3x= 10..312+8..274
Dấu chấm có nghĩa là dấu nhân!!
a) \(12\left(x-5\right)=7x-5\)
\(12x-60=7x-5\)
\(12x-7x=60-5\)
\(5x=55\)
\(x=11\)
a, 12(x-5)=7x-5
suy ra 12x-60-7x+5=0
suy ra 5x-55=0
suy ra x=55/5=11
vay x=11
b, ta có 5+2!3x-1/2!=6
suy ra 2!3x-1/2!=6-5=1
suy ra !3x-1/2!=1/2
xet th1: 3x-1/2=1/2
suy ra x=1/3
xet th2 3x-1/2=-1/2
suy ra x=0
vạy x=0 hoac x=1/3
c, (2x-3)^2010=(2x-3)^2012
xet th1 2x-3=1 suy ra x=2
xet th2 2x-*3=0 suy ra x=3/2
vạy x=2 hoac x=3/2
Bài 1:
a) 82 . 22 = 64 . 4 = 256
b) 25. 4 = 25. 22= 25+2 = 27
Có ai biết không giúp tôi với nhé
a) 0,5 + ( x - 15/2 ) : 1/2 = 9/2
<=> (x - 15/2 ): 1/2 = 9/2 - 0,5
<=> (x - 15/2) : 1/2 = 4
<=> (x - 15/2) = 4 . 1/2
<=> x - 15/2 = 2
<=> x = 2 + 15/2
<=> x = 19/2
b) 2012x - 2010x = 2014
( 2012 - 2010 ) .x = 2014
2x = 2014
x = 2014 :2
x = 1007