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A=-5,1+4,5+5,1-4,5
=(-5,1+5,1)+(4,5-4,5)
=0+0=0
B=-2,5x0,35x0,4-(-8)x3,5x0,125
=(-2,5x0,4)x0,35-(-8x0,125)x3,5
=-10x0,35-(-1)x3,5
=-3,5-(-3,5)
=7
k cho mình nha !!!
b) \(\left(x-1\right)^3=\dfrac{1}{8}\)
\(\left(x-1\right)^3=\left(\dfrac{1}{2}\right)^3\)
\(x-1=\dfrac{1}{2}\)
\(x=\dfrac{1}{2}+1\)
\(x=\dfrac{3}{2}\)
a, \(\dfrac{3}{7}\)\(x\) - 0,4 = - \(\dfrac{17}{35}\)
\(\dfrac{3}{7}\)\(x\) = - \(\dfrac{17}{35}\) + 0,4
\(\dfrac{3}{7}\)\(x\) = - \(\dfrac{3}{35}\)
\(x\) = - \(\dfrac{3}{35}\): \(\dfrac{3}{7}\)
\(x\) = - \(\dfrac{1}{5}\)
b, 0,2.(\(x\) - 3) +2,4 = 10
0,2.(\(x\) - 3) = 10 - 2,4
0,2.(\(x\) - 3) = 7,6
\(x\) - 3 = 7,6:0,2
\(x\) - 3 = 38
\(x\) = 38 + 3
\(x\) = 41
a) \(\left(-0,6\right)^6\cdot x=\left(\frac{-3}{5}\right)^8\)
\(x=\left(\frac{-3}{5}\right)^8:\left(\frac{-3}{5}\right)^6\)
\(x=\left(-\frac{3}{5}\right)^2=\frac{9}{25}\)
b) \(\left(0,5-x\right)^3=-8=\left(-2\right)^3\)
\(\Leftrightarrow0,5-x=-2\)
\(\Leftrightarrow x=2,5\)
Vậy,.................
a) \(3^{7x-1}=815\)
\(\Leftrightarrow3^{7x}:3=815\)
\(\Leftrightarrow\left(3^7\right)^x:3=815\)
\(\Leftrightarrow2187^x=815.3\)
\(\Leftrightarrow2187^x=2445\)
\(\Rightarrow\) Không có x thoả mãn.
b) \(\left(-0,6\right)^5.x=\left(\dfrac{-3}{5}\right)^8\)
\(\Leftrightarrow x=\left(\dfrac{-3}{5}\right)^8:\left(-0,6\right)^5\)
\(\Leftrightarrow x=\left(-0,6\right)^8:\left(-0,6\right)^5\)
\(\Leftrightarrow x=\left(-0,6\right)^3\)
c) \(\left(0,5-x\right)^3=-8\)
\(\Leftrightarrow\left(0,5-x\right)^3=\left(-2\right)^3\)
\(\Rightarrow0,5-x=-2\)
\(\Leftrightarrow x=0,5+2\)
\(\Leftrightarrow x=2,5\).
a) Quy đồng lên đi.
b) \(\frac{x+2}{0.5}=\frac{2x+1}{2}\Leftrightarrow\frac{x+2}{\left(\frac{1}{2}\right)}=\frac{2x+1}{2}\)
\(\Leftrightarrow2x+4=\frac{2x+1}{2}\Leftrightarrow4x+8=2x+1\)
\(\Leftrightarrow x=-\frac{7}{2}\)
c) \(\Leftrightarrow\left|x+\frac{1}{5}\right|=6\). VỚi x >= -1/5 thì:
\(x+\frac{1}{5}=6\Leftrightarrow x=\frac{29}{5}\left(TM\right)\)
Với x < -1/5 thì \(-x-\frac{1}{5}=6\Leftrightarrow x=-\frac{31}{5}\left(TM\right)\)
d) TƯơng tự ý a, quy đồng lên thôi (mẫu chung là 24 thì phải)
c) \(\left|x+\frac{1}{5}\right|-4=2\)
=> \(\left|x+\frac{1}{5}\right|=2+4\)
=> \(\left|x+\frac{1}{5}\right|=6\)
=> \(\left\{{}\begin{matrix}x+\frac{1}{5}=6\\x+\frac{1}{5}=-6\end{matrix}\right.\) => \(\left\{{}\begin{matrix}x=6-\frac{1}{5}\\x=\left(-6\right)-\frac{1}{5}\end{matrix}\right.\)
=> \(\left\{{}\begin{matrix}x=\frac{29}{5}\\x=-\frac{31}{5}\end{matrix}\right.\)
Vậy \(x\in\left\{\frac{29}{5};-\frac{31}{5}\right\}\).
Mình chỉ làm câu c) thôi nhé.
Chúc bạn học tốt!
tìm nghiệm của đa thức một biến:
a, x(x-5)-(x-5)*(3x+2)
b,2*(0,3x-0,5x)-0,5(3-x)
c,(x-1)-(x-2)=(-x-40-8
a. \(x\left(x-5\right)-\left(x-5\right)\left(3x+2\right)=0\)
\(\Rightarrow\left(x-5\right)\left[x-\left(3x+2\right)\right]=0\)
\(\Rightarrow\left(x-5\right)\left(x-3x-2\right)=0\)
\(\Rightarrow\left(x-5\right)\left(-2x-2\right)=0\)
\(\Rightarrow-2\left(x-5\right)\left(x+1\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}-2\ne0\\x-5=0\\x+1=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}-2\ne0\\x=5\\x=-1\end{matrix}\right.\)
b. \(2\left(0,3x-0,5x\right)-0,5\left(3-x\right)=0\)
\(\Rightarrow-0,4x-1,5+0,5x=0\)
\(\Rightarrow0,1x-1,5=0\)
\(\Rightarrow0,1x=1,5\)
\(\Rightarrow x=\dfrac{1,5}{0,1}=15\)
c. \(\left(x-1\right)-\left(x-2\right)=\left(-x-40\right)-8\)
\(\Rightarrow x-1-x+2=-x-40-8\)
\(\Rightarrow1=-x-48\)
\(\Rightarrow1+48=-x\)
\(\Rightarrow x=-49\)
\(x:5=8.\dfrac{1}{2}\\ x:5=4\\ x=20\)