\(\left(8x-1\right)^{2x+1}\)=\(^{5^{2n+1}}\)
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: \(=2x^{2n+1-2n}-6x^{2n+2-2n}+3x^{2n-1+1-2n}-9x^{2n-1+2-2n}\)
\(=2x-6x^2+3-9x\)
\(=-6x^2-7x+3\)
Bài 1: Thực hiện phép tính:
A = \(\left(2x^{2n}+3x^{2n-1}\right)\left(x^{1-2n}-3x^{2-2n}\right)\)
B = \(\left(3x^{2m-1}-\frac{3}{7}y^{3n-5}+x^{2m}y^{3n}-3y^2\right).8x^{3-2m}y^{6-3n}\)
\(\left(8x-7\right)\left(8x-5\right)\left(2x-1\right)\left(4x-1\right)=9\)
Lời giải:
PT \(\Leftrightarrow [(8x-7)(4x-1)][(8x-5)(2x-1)]=9\)
\(\Leftrightarrow (32x^2-36x+7)(16x^2-18x+5)=9\)
Đặt \(16x^2-18x=a\). PT trở thành:
\((2a+7)(a+5)=9\)
\(\Leftrightarrow 2a^2+17a+26=0\)
\(\Rightarrow \left[\begin{matrix} a=-2\\ a=\frac{-13}{2}\end{matrix}\right.\)
\(a=-2\Leftrightarrow 16x^2-18x+2=0\)
\(\Leftrightarrow (8x-1)(x-1)=0\Rightarrow \left[\begin{matrix} x=1\\ x=\frac{1}{8}\end{matrix}\right.\)
\(a=\frac{-13}{2}\Leftrightarrow 16x^2-18x+\frac{13}{2}=0\) (pt vô nghiệm)
Vậy............
Tìm n , biết
\(\left(8x-1\right)^{2n+1}=5^{2n+1}\)
\(\left(8x-1\right)^{2n+1}=5^{2n+1}\)
\(\Leftrightarrow8x-1=5\)
\(\Leftrightarrow x=\frac{3}{4}\)
\(\left(8x-1\right)^{2n+1}=5^{2n+1}\)
\(\Rightarrow8x-1=5\)
\(\Rightarrow8x=6\)
\(\Rightarrow x=\frac{3}{4}\)
Vậy \(x=\frac{3}{4}\)
Tìm x biết:
c )\(\left(8x-1\right)^{2n+1}=5^{2n+1}\)
(8x - 1)2n+1 = 52n+1 ( lũy thừa bậc lẻ )
8x - 1 = 5
8x = 6
x = 3/4
\(\left(8x-1\right)^{2n+1}=5^{2n+1}\Rightarrow8x-1=5\Rightarrow8x=6\Rightarrow x=\frac{6}{8}\)
Tìm x biết: \(\left(8x-1\right)^{2n+1}=5^{2n+1}\)
\(\left(8x-1\right)^{2n+1}=5^{2n+1}\)
\(8x-1=5\)
\(8x=6\)
\(x=\dfrac{3}{4}\)
=.= hok tốt!!
Giải các phương trình sau:
a)\(\frac{\left(9x-0.7\right)}{4}-\frac{\left(5x-1.5\right)}{7}=\frac{\left(7x-1.1\right)}{3}-\frac{5\left(0.4-2x\right)}{6}\)
b)\(\frac{3x-1}{x-1}-\frac{2x+5}{x+3}=1-\frac{4}{\left(x-1\right)\left(x+3\right)}\)
c)\(\frac{3}{4\left(x-5\right)}+\frac{15}{50-2x^2}=-\frac{7}{6\left(x+5\right)}\)
d)\(\frac{8x^2}{3\left(1-4x\right)^2}=\frac{2x}{6x-3}-\frac{1+8x}{4+8x}\)
Tìm x biết:
\(\left(x-7\right)^{x+1}-\left(x-7\right)^{x+11}=0\)
\(\left(8x-1\right)^{2n+1}=5^{2n+1}\)
(x-7)x+1-(x-7)x+11=0
=>x-7=0
=>x=7
(8x-1)2n+1=52n+1
=>8x-1=5
=>8x=6
=>x=3/4
Tick Đúng Nha
Tim x biet : \(\left(8x-1\right)^{2n+1}=5^{2n+1}\)
nếu n E N thì 2n+1 là số lẻ lúc đó ta có:
(8x-1)2n+1 = 52n+1
<=> 8x - 1 = 5
<=> 8n = 6
<=> n = 6/8 = 3/4