cho t=6x+1/3x-1 tim gthln
Tim x biet: (3/4x+5)-(2/3x-4)-(1/6x+1)=(1/3+4)-(1/3x-3)
\(\left(\dfrac{3x}{4}+5\right)-\left(\dfrac{2x}{3}-4\right)-\left(\dfrac{x}{6}+1\right)=\left(\dfrac{1}{3}+4\right)-\left(\dfrac{1}{3}x-3\right)\)
\(\Leftrightarrow\dfrac{3x}{4}-\dfrac{2x}{3}-\dfrac{x}{6}+5+4-1=\dfrac{13}{3}-\dfrac{1}{3}x+9\)
\(\Leftrightarrow\dfrac{9x-8x-2x}{12}+8=\dfrac{13-x}{3}+\dfrac{27}{3}\)
\(\Leftrightarrow\dfrac{-x}{12}+\dfrac{96}{12}=\dfrac{40-x}{3}\Leftrightarrow\dfrac{96-x}{12}=\dfrac{160-4x}{12}\)
\(\Rightarrow96-160=-4x+x\Leftrightarrow-64=-3x\Leftrightarrow x=\dfrac{64}{3}\)
Tim x biet:
(3/4x + 5) - (2/3x - 4) - (1/6x + 1) = (1/3x + 4) - (1/3x - 3)
3/4x + 5-(2/3x-4)-(1/6+1)=(1/3x+4)-(1/3x-3)
=3/4x+5-2/3x-4-1/6x+1=1/3x+4-1/3x-3
=-1/12=7
x=84
Đ/S...
tim so nguyen x: (12x-1)(6x-1)(4x-1)(3x-1)=330
cách 1: phân tích ra ước
cách 2 áp dụng 7 hằng đẳng thức nhân tung ra
ko f l tfboys mà là TFBOYS nhé , bn có f Tứ Diệp Thảo ko vx
Tim a để đa thức x4+6x3+7x2-6x+a chia hết cho x2+3x-1
tim x
(12x-5)(4x-1)+(3x-7)(1-6x)=81
<=> 48x^2 - 12x - 20x + 5 + 3x - 48x^2 - 7 + 112x = 81
<=> -32x + 115x = 81 + 2
<=> 83x = 83
<=> x = 1
Bài 5: Cho đa thức A = 3x ^ 3 - 4x + 1 Tim đa thức B biết: a) B / A = 5x + 3 b) A. B = 3x ^ 4 + 6x ^ 3 - 4x ^ 2 - 7x + 2
a: B=A(5x+3)
=(3x^3-4x+1)(5x+3)
=15x^4+9x^3-20x^2-12x+5x+3
=15x^4+9x^3-20x^2-7x+3
b: \(B=\dfrac{3x^4+6x^3-4x^2-7x+2}{3x^3-4x+1}\)
\(=\dfrac{3x^4-4x^2+x+6x^3-8x+2}{3x^3-4x+1}\)
=x+2
Cho B = [ 3x/( 1-3x ) + 2x/(3x+1) ] : 6x^2 + 10x/1-6x + 9x^2
a,Rút gọn B
b, Tính gtrị của B khi B = 1/3
c, tìm x để B > 0
a) Điều kiện : \(x\ne\pm\dfrac{1}{3}\)
\(B=\left[\dfrac{3x}{1-3x}+\dfrac{2x}{3x+1}\right]:\dfrac{6x^2+10x}{1-6x+9x^2}\)
\(=\left(\dfrac{3x\left(3x+1\right)}{\left(1-3x\right)\left(3x+1\right)}+\dfrac{2x\left(1-3x\right)}{\left(1-3x\right)\left(3x+1\right)}\right):\dfrac{6x^2+10x}{ \left(3x-1\right)^2}\)
\(=\dfrac{9x^2+3x+2x-6x^2}{\left(1-3x\right)\left(3x+1\right)}\cdot\dfrac{\left(1-3x\right)^2}{6x^2+10x}\)
\(=\dfrac{x\left(3x+5\right)}{\left(1-3x\right)\left(3x+1\right)}\cdot\dfrac{\left(1-3x\right)^2}{2x\left(3x+5\right)}=\dfrac{1-3x}{2\left(3x+1\right)}\)
b) Sai đề = Không làm
c) B >0
=> \(\left[{}\begin{matrix}\left\{{}\begin{matrix}1-3x>0\\2\left(3x+1\right)>0\end{matrix}\right.\\\left[{}\begin{matrix}1-3x< 0\\2\left(3x+1\right)< 0\end{matrix}\right.\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x< \dfrac{1}{3}\\x>-\dfrac{1}{3}\end{matrix}\right.\\\left\{{}\begin{matrix}x>\dfrac{1}{3}\\x< -\dfrac{1}{3}\end{matrix}\right.\end{matrix}\right.\)
TH1 => \(-\dfrac{1}{3}< x< \dfrac{1}{3}\)
TH2 :Vô lí
Vậy giá trị x thỏa mãn :
\(-\dfrac{1}{3}< x< \dfrac{1}{3}\)
Tim TGNN của BT. A=6x/x-1/+/3x-2/+2x
Cho biểu thức A= ( 3x-1/3x+1 - 3x+1/3x-1) nhân 6x-2/3x
a, Tìm ĐKXĐ.RÚT GỌN
b, Tìm x để |A|= 2