50x\(\dfrac{2}{3}\)
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\(M=\dfrac{3}{2}\cdot4\sqrt{2x}-\dfrac{1}{3}\cdot3\sqrt{2x}+\dfrac{2}{5}\cdot5\sqrt{2x}-4\sqrt{2x}=6\sqrt{2x}-\sqrt{2x}+2\sqrt{2x}-4\sqrt{2x}=3\sqrt{2x}\)
\(M=6\sqrt{2x}-\sqrt{2x}+2\sqrt{2x}-4\sqrt{2x}=3\sqrt{2x}\)
Bài 1:
\(a,=\dfrac{x^2+2xy+y^2-x^2+2xy-y^2+2y^2}{2\left(x-y\right)\left(x+y\right)}=\dfrac{2y\left(x+y\right)}{2\left(x-y\right)\left(x+y\right)}=\dfrac{y}{x-y}\\ b,Sửa:\left(\dfrac{9}{x^3-9x}+\dfrac{1}{x+3}\right):\left(\dfrac{x-3}{x^2+3x}-\dfrac{x}{3x+9}\right)\\ =\dfrac{9+x^2-3x}{x\left(x-3\right)\left(x+3\right)}:\dfrac{3x-9-x^2}{3x\left(x+3\right)}=\dfrac{x^2+3x+9}{x\left(x-3\right)\left(x+3\right)}\cdot\dfrac{-3x\left(x+3\right)}{x^2-3x+9}\\ =\dfrac{-3}{x-3}\)
Bài 2:
\(a,\Leftrightarrow2x\left(x-5\right)\left(x+5\right)=0\Leftrightarrow\left[{}\begin{matrix}x=0\\x=5\\x=-5\end{matrix}\right.\\ b,\Leftrightarrow x^3+x^2+x+a=\left(x+1\right)\cdot a\left(x\right)\\ \text{Thay }x=-1\Leftrightarrow-1+1-1+a=0\Leftrightarrow a=1\)
a) Ta có: \(\dfrac{x^2}{y^2}:\sqrt{\dfrac{x^2}{y^4}}\)
\(=\dfrac{x^2}{y^2}:\dfrac{x}{y^2}\)
=x
b) Ta có: \(\sqrt{\dfrac{27\left(x-1\right)^2}{12}}+\dfrac{3}{2}-\left(x-2\right)\sqrt{\dfrac{50x^2}{8\left(x-2\right)^2}}\)
\(=\sqrt{\dfrac{9}{4}}\cdot\sqrt{\left(x-1\right)^2}+\dfrac{3}{2}-\left(x-2\right)\cdot\sqrt{\dfrac{25}{4}}\cdot\sqrt{\dfrac{x^2}{\left(x-2\right)^2}}\)
\(=\dfrac{3}{2}\cdot\left(x-1\right)+\dfrac{3}{2}-\left(x-2\right)\cdot\dfrac{5}{2}\cdot\dfrac{x}{2-x}\)
\(=\dfrac{3}{2}x-\dfrac{3}{2}+\dfrac{3}{2}-\dfrac{5}{2}\left(x-2\right)\cdot\dfrac{-x}{x-2}\)
\(=\dfrac{3}{2}x+\dfrac{5}{2}\cdot\left(x\right)\)
=4x
`\sqrt{[27(x-1)^2]/12} +3/2 - (x - 2)\sqrt{[50x^2]/[8(x-2)^2]}` `(1 < x < 2)`
`=\sqrt{[3(x-1)]^2 .3}/\sqrt{2^2 .3} + 3/2 - (x - 2) \sqrt{(5x)^2 . 2}/\sqrt{[2(x - 2)]^2 . 2}`
`=[3\sqrt{3}|x-1|]/[2\sqrt{3}]+3/2-(x-2)[5\sqrt{2}|x|]/[2\sqrt{2}|x-2|]`
`=[3(x-1)]/2+3/2-[5x(x-2)]/[2(2-x)]` (Vì `1 < x < 2`)
`=3/2x - 3/2 + 3/2 + 5/2x`
`=4x`
f(x)= x^6 - 50x^5+50x^4-50x^3+50x^2-50x+50 tại x=49
<=> \(f_{\left(49\right)}\)= 49^6 - 50.49^5+50.49^4-50.49^3+50.49^2-50.49+50
<=> \(f_{\left(49\right)}\)= 13519544083, 0396489851
Ta có: \(\sqrt{4.5x}+\sqrt{50x}-\sqrt{32x}+\sqrt{72x}-5\sqrt{\dfrac{x}{2}}-12=0\)
\(\Leftrightarrow\dfrac{3\sqrt{2}}{2}\sqrt{x}+5\sqrt{2}\sqrt{x}-4\sqrt{2}\sqrt{x}+6\sqrt{2}\sqrt{x}-\dfrac{5\sqrt{2}}{2}\sqrt{x}-12=0\)
\(\Leftrightarrow6\sqrt{2x}=12\)
\(\Leftrightarrow\sqrt{2x}=2\)
\(\Leftrightarrow2x=4\)
hay x=2
\(x-\left(\dfrac{50x}{100}+\dfrac{25x}{100}\right)=11\dfrac{1}{4}\)
\(x-\dfrac{3x}{4}=\dfrac{45}{4}\)
\(\dfrac{x}{4}=\dfrac{45}{4}\Rightarrow x=45\)
\(x=49\Leftrightarrow50=x+1\)
Tính A = x7 - 50x6 + 50x5 - 50x4 + 50x3 - 50x2 +50x +100 với x = 49
\(\Rightarrow A=x^7-\left(x+1\right)x^6+\left(x+1\right)x^5-\left(x+1\right)x^4+\left(x+1\right)x^3-\left(x+1\right)x^2+\left(x+1\right)x+100\)
\(=x^7-\left(x^7+x^6\right)+\left(x^6+x^5\right)-\left(x^5+x^4\right)+...+\left(x^2+1\right)+100\)
\(=x+100=149\)
\(50\times\dfrac{2}{3}\)
\(=\dfrac{50\times2}{3}\)
\(=\dfrac{100}{3}\)
50x\(\dfrac{2}{3}\)
=\(\dfrac{50}{1}\)x\(\dfrac{2}{3}\)
=\(\dfrac{100}{3}\)