Cho \(\frac{a}{b}=\frac{c}{d}\)Chứng tỏ :
a,\(\frac{2+ab}{b}=\frac{c+2d}{d}\)
b, \(\frac{b-3a}{a}=\frac{d-3c}{c}\)
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\(1024:2^6+160:\left(3^3+53\right)-9^{100}:9^{99}\)
\(=2^{10}:2^6+160:\left(26+53\right)-9\)
\(=2^4+160:80-9\)
\(=16+2-9\)
\(=9\)
saii đề bài ak,
Tìm x:1. / x+1/+/3-2x/=/3x-2/
2. /x-3/-2/5-2x/=11
Ko có giá trị tuyệt đối nên mk dùng tạm dấu gạch ngang
\(\left|x+3\right|=\left|5-2x\right|\)
TH1 : \(x+3=5-2x\Leftrightarrow3x=2\Leftrightarrow x=\frac{2}{3}\)
TH2 : \(x+3=2x-5\Leftrightarrow x=8\)
\(a,\frac{x+2}{-15}=\left(-\frac{5}{3}\right)\)
\(\Leftrightarrow\left(-\frac{x+2}{15}\right)=\left(-\frac{5}{3}\right)\)
\(\Leftrightarrow\left(-3\right)\times\left[-\left(x+2\right)\right]=15\times5\)
\(\Leftrightarrow3x+6=75\)
\(\Leftrightarrow3x=69\)
\(\Leftrightarrow x=23\)
\(a)\)
\(f\left(x\right)=-x^3+3x^2+x-3+2^3-x^2\)
\(\Leftrightarrow f\left(x\right)=-x^3+\left(3x^2-x^2\right)+x-3+2^3\)
\(\Leftrightarrow f\left(x\right)=-x^3+2x^2+x-3+8\)
\(\Leftrightarrow f\left(x\right)=-x^3+2x^2+x+5\)
\(g\left(x\right)=-3x^3-x^2+2x^3+5x-3-4x\)
\(\Leftrightarrow g\left(x\right)=\left(-3x^3+2x^3\right)-x^2+\left(5x-4x\right)-3\)
\(\Leftrightarrow g\left(x\right)=-x^3-x^2+x-3\)
\(b)\)
Theo đề ra: \(h\left(x\right)=f\left(x\right)+g\left(x\right)\)
\(f\left(x\right)=-x^3+2x^2+x+5\)
\(g\left(x\right)=-x^3-x^2+x-3\)
\(\Rightarrow h\left(x\right)=x^2+2x+2\)
a, \(\left|x-1\right|=3x+2\)ĐK : x >= -2/3
TH1 : \(x-1=3x+2\Leftrightarrow2x=-3\Leftrightarrow x=-\frac{3}{2}\)( ktm )
TH2 : \(x-1=-3x-2\Leftrightarrow4x=-1\Leftrightarrow x=-\frac{1}{4}\)( tm )
b, \(\left|5x\right|=x-12\)ĐK : x > = 12
TH1 : \(5x=x-12\Leftrightarrow4x=-12\Leftrightarrow x=-3\)( ktm )
TH2 : \(5x=12-x\Leftrightarrow6x=12\Leftrightarrow x=2\)( ktm )
c, \(\left|7-x\right|=5x+1\)ĐK : x >= -1/5
TH1 : \(7-x=5x+1\Leftrightarrow6x=-6\Leftrightarrow x=-1\)( ktm )
TH2 : \(7-x=5x+1\Leftrightarrow6x=6\Leftrightarrow x=1\)( tm )
a) Điều kiện : \(x\ge-\frac{2}{3}\)
Xét :
\(\Rightarrow x-1< 0\)
\(\Rightarrow\left|x-1\right|=1-x\)
\(\Rightarrow1-x=3x+2\)
\(\Rightarrow4x=-1\)
\(\Rightarrow x=-\frac{1}{4}\left(TM\right)\)
\(\Rightarrow x-1\ge0\)
\(\Rightarrow\left|x-1\right|=x-1\)
\(\Rightarrow x-1=3x+2\)
\(\Rightarrow2x=-3\)
\(\Rightarrow x=-\frac{3}{2}\left(KTM\right)\)
Vậy \(x=-\frac{1}{4}\)
b) Điều kiện : \(x\ge12\)
\(\Rightarrow5x>0\)
\(\Rightarrow\left|5x\right|=5x\)
\(\Rightarrow5x=x-12\)
\(\Rightarrow4x=-12\)
\(\Rightarrow x=-3\left(KTM\right)\)
Vậy không có x
c)Điều kiện : \(x\ge-\frac{1}{5}\)
Xét :
\(\Rightarrow7-x\ge0\)
\(\Rightarrow\left|7-x\right|=7-x\)
\(\Rightarrow7-x=5x+1\)
\(\Rightarrow6x=6\)
\(\Rightarrow x=1\left(TM\right)\)
\(\Rightarrow7-x< 0\)
\(\Rightarrow\left|7-x\right|=x-7\)
\(\Rightarrow x-7=5x+1\)
\(\Rightarrow4x=-8\)
\(\Rightarrow x=-2\left(KTM\right)\)
Vậy \(x=1\)