Tìm x:
a) 8/9 nhân x trừ 2/3 = 1/3 nhân x + 1 và 1/3
b) (x - 1/2) nhân ( 3/2 - 2x) = 0
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bài 1 tính giá trị biểu thức
( - 25 ) nhân ( -3 ) nhân x với x = 4
\(\left(-25\right).\left(-3\right).4\)
\(=\left(-25\right).4.\left(-3\right)\)
\(=-100.\left(-3\right)=300\)
( -1 ) nhân ( -4 ) nhân 5 nhân 8 nhân y với y =25
\(\left(-1\right).\left(-4\right).5.8.25\)
\(=4.5.8.25=4.25.5.8\)
\(=100.40=40000\)
( 2ab mũ 2 ) : c với a =4 ; b= -6 ; c =12
\(\left(2.4.\left(-6\right)\right)^2:12\)
\(=\left(-48\right)^2:12\)
\(=2304:12=192\)
[ ( -25 ) nhân ( - 27 ) nhân ( -x ) ] : y với x = 4 ; y = -9
\(\left[\left(-25\right).\left(-27\right).\left(-4\right)\right]:-9\)
\(=-2700:\left(-9\right)\)
\(=300\)
(a mũ 2 _ b mũ 2) : ( a + b ) nhân ( a _ b ) với a + 5 , b = -3
\(\left(5^2-\left(-3\right)^2\right):\left(5-3\right).\left(5+3\right)\)
\(=16:2.8\)
\(=8.8=64\)
1/
\(B=\frac{\left(3-1\right)\left(3+1\right)\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)-3^{16}}{4}\)
\(=\frac{\left(3^2-1\right)\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)-3^{16}}{4}\)
\(=\frac{\left(3^4-1\right)\left(3^4+1\right)\left(3^8+1\right)-3^{16}}{4}\)
\(=\frac{\left(3^8-1\right)\left(3^8+1\right)-3^{16}}{4}\)
\(=\frac{3^{16}-1-3^{16}}{4}=\frac{-1}{4}\)
2/
a, (x-5)2-(x+3)2=1
<=>(x-5+x+3)(x-5-x-3)=1
<=>-16.(x-1)=1
<=>x-1=-1/16
<=>x=15/16
b, (2x-1)2-(2x-3)2=4
<=>(2x-1+2x-3)(2x-1-2x+3)=4
<=>-8(x-1)=4
<=>x-1=-1/2
<=>x=1/2
\(\frac{1}{9}.3^4.3^x=3^7\)
\(\Leftrightarrow3^x=3^7:\frac{1}{9}:3^4=243\)
\(\Leftrightarrow3^x=3^5\)
\(\Leftrightarrow x=5\)
a: \(=\dfrac{3}{5}\cdot\dfrac{5}{4}+\dfrac{1}{2}\cdot\dfrac{2}{3}=\dfrac{3}{4}+\dfrac{1}{3}=\dfrac{9+4}{12}=\dfrac{13}{12}\)
b: \(\Leftrightarrow x\cdot\dfrac{5}{4}=\dfrac{5}{8}\)
hay x=1/2
10/3 x 1/2 - ( 1/2 x X - 1/3) + 1/5 = 3/5 :1/2
5/3 - ( 1/2 x X - 1/3) + 1/5 = 6/5
5/3 - ( 1/2 x X - 1/3) = 6/5 + 1/5
5/3 - ( 1/2 x X - 1/3) = 7/5
1/2 x X - 1/3 = 5/3 - 7/5
1/2 x X - 1/3 = 4/15
1/2 x X = 4/15 + 1/3
1/2 x X = 9/15
X = 9/15 : 1/2
X = 18/15.
\(a.x+\dfrac{3}{7}=\dfrac{2}{5}:\dfrac{18}{35}\\x+\dfrac{3}{7}=\dfrac{2}{5}\times\dfrac{35}{18} \\ x+\dfrac{3}{7}=\dfrac{7}{9}\\ x=\dfrac{7}{9}-\dfrac{3}{7}\\ x=\dfrac{22}{63}\)
\(b.x\times\dfrac{5}{9}=\dfrac{4}{5}-\dfrac{1}{3}\\x\times\dfrac{5}{9}=\dfrac{7}{15}\\ x=\dfrac{7}{15}:\dfrac{5}{9}\\ x= \dfrac{21}{25}\)
a) \(\frac{8}{9}\cdot x-\frac{2}{3}=\frac{1}{3}\cdot x+1\frac{1}{3}\)
=> \(\frac{8x}{9}-\frac{2}{3}=\frac{x}{3}+\frac{4}{3}\)
=> \(\frac{8x}{9}-\frac{6}{9}=\frac{x+4}{3}\)
=> \(\frac{8x-6}{9}=\frac{x+4}{3}\)
=> \(3\left(8x-6\right)=9\left(x+4\right)\)
=> \(24x-18=9x+36\)
=> \(24x-18-9x=36\)
=> \(24x-9x=54\)
=> \(15x=54\)
=> \(5x=18\)
=> \(x=\frac{18}{5}\)
Vậy x = \(\frac{18}{5}\)
b) \(\left(x-\frac{1}{2}\right)\left(\frac{3}{2}-2x\right)=0\)
=> \(\orbr{\begin{cases}x-\frac{1}{2}=0\\\frac{3}{2}-2x=0\end{cases}}\)
=> \(\orbr{\begin{cases}x=\frac{1}{2}\\2x=\frac{3}{2}\end{cases}}\)
=> \(\orbr{\begin{cases}x=\frac{1}{2}\\x=\frac{3}{2}:2=\frac{3}{4}\end{cases}}\)
Vậy \(x\in\left\{\frac{1}{2};\frac{3}{4}\right\}\)