Tích \(\left(2.x^{2n}+3.x^{2n-1}\right).\left(x^{1-2n}-3.x^{2-2n}\right)\)\(\left(2.x^{2n}+3.x^{2n-1}\right).\left(x^{1-2n}-3.x^{2-2n}\right)\).
Giup nhs..
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Bài 1: Làm tính nhân
a. \(\left(2x^{2n}+3x^{2n-1}\right)\left(x^{1-2n}-3x^{2-2n}\right)\)
b. \(\left(25x^2+10xy+4y^2\right)\left(5x-2y\right)\)
c. \(\left(5x^3-x^2+2x-3\right)\left(4x^2-x+2\right)\)
a: \(=2x^{2n+1-2n}-2\cdot x^{2n}\cdot3\cdot x^{2-2n}+3\cdot x^{2n-1+1-2n}-9\cdot x^{2n-1+2-2n}\)
\(=2x-6x^2+3-9x\)
\(=-6x^2-7x+3\)
b: \(=\left(5x\right)^3-\left(2y\right)^3=125x^3-8y^3\)
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Làm tính nhân: a. \(\left(3x^{2m-1}-\dfrac{3}{7}y^{3n-5}+x^{2m}y^{3m}-3y^2\right)8x^{3-2m}y^{6-3n}\)
b.\(\left(2x^{2n}+3x^{2n-1}\right)\left(x^{1-2n}-3x^{2-2n}\right)\)
a: \(=24x^{2m-1+3-2m}y^{6-3m}-\dfrac{24}{7}y^{3n-7+6-3n}\cdot x^{3-2m}+8x^{3-2m+2m}\cdot y^{6-3n+3m}-24x^{3-2m}y^{6-2n+2}\)
\(=24x^2y^{6-3m}-\dfrac{24}{7}x^{3-2m}\cdot y^{-1}+8x^3y^{-3n+3m+6}-24x^{3-2m}y^{-2n+8}\)
b: \(=2x^{2n+1-2n}-6x^{2n+2-2n}+3x^{2n-1+1-2n}-9x^{2n-1+2-2n}\)
\(=2x-6x^2+3-9x\)
\(=-6x^2-7x+3\)
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tính các giới hạn sau :a/ \(lim\dfrac{3x^2 3}{x 1}\left(x\rightarrow1\right)\)b/ \(lim\dfrac{2^n 2.4^n}{4.4^n-3.2^n}\)c/ \(lim\dfrac{\left(2n^2 1\right)\left(2n^5 n\right)}{n^7 2}\)d/ \(lim\dfrac{2x 1}{\left(x-2\right)^2}\left(x\rightarrow2\right)\)e...
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Bài 1: Thực hiện phép tính:
A = \(\left(2x^{2n}+3x^{2n-1}\right)\left(x^{1-2n}-3x^{2-2n}\right)\)
B = \(\left(3x^{2m-1}-\frac{3}{7}y^{3n-5}+x^{2m}y^{3n}-3y^2\right).8x^{3-2m}y^{6-3n}\)
Tìm x:
\(\frac{1}{3}x+\frac{2}{5}\left(x-1\right)=0\)
\(\left(2n-3\right)\left(6-2n\right)=0\)
\(\frac{-2}{3}-\frac{1}{3}\left(2z-5\right)=\frac{3}{2}\)
a) 1/3x + 2/5x - 2/5 = 0
=> x = 0,54
b) 12n - 4n^2 - 18 + 6n +0
<=> -4n^2 + 6n - 18 = 0
<=> (-4n)^2 + 6n + 12n - 18 +0
<=> - 2n (2n-3 ) + 6 ( 2n - 3 ) = 0
,<=> ( 6 - 2n ) ( 2n -3 )=0
<=> 6 - 2n = 0 => n +3 / 2n-3 =0 => n = 3/2
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Cho em hỏi bài này ạ
Cho:
\(f\left(x\right)=x^{2n}-x^{2n-1}+...+x^2-x+1\)
\(g\left(x\right)=-x^{2n+1}+x^{2n}-x^{2n-1}+...+x^2-x+1\)
Tính giá trị của hiệu \(f\left(x\right)-g\left(x\right)\)tại \(x=\frac{1}{10}\)
\(\left(2x^{2n}+3x^{2n-1}\right)\cdot\left(x^{1-2n}-3x^{2-2n}\right)\)
. Thực hiện phép chia:a) \(\left(2n^3-5n^2+1\right):\left(2n-1\right)\)
b) \(\left(\frac{x^2}{x^3-4x}+\frac{6}{6-3x}+\frac{1}{x+2}\right):\left(x-2+\frac{10-x^2}{x+2}\right)\)
c) \(\left(1-3x\right)^2+2\left(3x-1\right)\left(3x+4\right)+\left(3x+4\right)^2\)
a/ \(\left(2n^3-5n^2+1\right):\left(2n-1\right)=n^2-2n-1\)
b/ \(x\ne0;\pm2\)
\(\left(\frac{x^2}{x\left(x^2-4\right)}-\frac{6}{3\left(x-2\right)}+\frac{1}{x+2}\right):\left(\frac{x^2-4+10-x^2}{x+2}\right)\)
\(=\left(\frac{x}{x^2-4}-\frac{2\left(x+2\right)}{x^2-4}+\frac{x-2}{x^2-4}\right):\left(\frac{6}{x+2}\right)\)
\(=\left(\frac{x-2x-4+x-2}{\left(x-2\right)\left(x+2\right)}\right).\left(\frac{x+2}{6}\right)\)
\(=\frac{-6}{\left(x-2\right)\left(x+2\right)}.\frac{\left(x+2\right)}{6}=-\frac{1}{x-2}=\frac{1}{2-x}\)
c/
\(\left(3x-1\right)^2+2\left(3x-1\right)\left(3x+4\right)+\left(3x+4\right)^2\)
\(=\left(3x-1+3x+4\right)^2\)
\(=\left(6x+3\right)^2\)
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Tìm x biết: \(\left(x+3\right)^{2n+1}=\left(2x-3\right)^{2n+1}\)
\(\left(x+3\right)^{2n+1}=\left(2x-3\right)^{2n+1}\)
\(\Rightarrow\left(x+3\right)=\left(2x-3\right)\)
\(\Rightarrow x+3=2x-3\)
\(\Rightarrow x+3-2x+3=0\)
\(\Rightarrow-x+6=0\)
\(\Rightarrow x=6\)
Vậy x=6
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\(\left(x+3\right)^{2n+1}=\left(2x-3\right)^{2n+1}\)
\(\Rightarrow x+3=2x-3\)
\(x+3-2x+3=0\)
\(\left(x-2x\right)+\left(3+3\right)=0\)
\(-x+6=0\)
\(-x=0-6\)
\(-x=-6\)
\(\Rightarrow x=6\)
Vậy \(x=6\).
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