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H9
HT.Phong (9A5)
CTVHS
30 tháng 7 2023
\(\left(12x-5\right)\left(4x-1\right)\left(3x-7\right)\left(1-16x\right)=81\)
\(\Rightarrow\left(48x^2-12x-20x+5\right)\left(3x-7\right)\left(1-16x\right)=81\)
\(\Rightarrow\left(48x^2-32x+5\right)\left(3x-7\right)\left(1-16x\right)=81\)
\(\Rightarrow\left(144x^3-336x^2-96x^2+224x+15x-35\right)\left(1-16x\right)=81\)
\(\Rightarrow\left(144x^3-432x^2+239x-35\right)\left(1-16x\right)=81\)
\(\Rightarrow144x^3-2304x^4-432x^2+6912x^3+239x-3824x^2-35+560x=81\)
\(\Rightarrow-2304x^4+7056x^3-4256x^2+799x-116=0\)
\(\Rightarrow\left[{}\begin{matrix}x_1\approx2,3\\x_2\approx0,5\end{matrix}\right.\)
20 tháng 8 2017
a)\(4x\left(x-5\right)-\left(x-1\right)\left(4x-3\right)=5\)
\(4x^2-20x-\left(4x^2-7x+3\right)=5\)
\(4x^2-20x-4x^2+7x-3=5\)
\(-13x=8\)
\(x=-\frac{8}{13}\)
b)\(\left(12x-5\right)\left(4x-1\right)+\left(3x-7\right)\left(1-16x\right)=81\)
\(48x^2-32x+5+3x-48x^2-7+112x=81\)
\(83x-2=81\)
\(x=1\)
DK
1
HH
6 tháng 5 2018
a/ \(\left(x-1\right)\left(x^2+x+1\right)=-9\)
=> \(x^2\left(x-1\right)+x\left(x-1\right)+\left(x-1\right)=-9\)
=> \(x^3-x^2+x^2-x+x-1=-9\)
=> \(x^3+\left(x^2-x^2\right)+\left(x-x\right)-1=-9\)
=> \(x^3-1=-9\)
=> \(x^3=-8\)
=> \(x=-2\)
b/ \(\left(12x-5\right)\left(4x-1\right)+\left(3x-7\right)\left(1-16x\right)=81\)
=> \(48x^2-12x-20x+5+3x-48x^2-7+112x=81\)
=> \(\left(48x^2-48x^2\right)+\left(112x-12x-20x+3x\right)+\left(5-7\right)=81\)
=> \(83x-2=81\)
=> \(83x=83\)
=> x = 1
14 tháng 4 2023
a: =x^4-3x^5+4x^8
b: =2x^3+2x^2+4x
c: =4x^2+8x-5
d: =2x+3x^2+7x^4
KH
22 tháng 9 2018
* Trả lời:
\(\left(1\right)\) \(-3\left(1-2x\right)-4\left(1+3x\right)=-5x+5\)
\(\Leftrightarrow-3+6x-4-12x=-5x+5\)
\(\Leftrightarrow6x-12x+5x=3+4+5\)
\(\Leftrightarrow x=12\)
\(\left(2\right)\) \(3\left(2x-5\right)-6\left(1-4x\right)=-3x+7\)
\(\Leftrightarrow6x-15-6+24x=-3x+7\)
\(\Leftrightarrow6x+24x+3x=15+6+7\)
\(\Leftrightarrow33x=28\)
\(\Leftrightarrow x=\dfrac{28}{33}\)
\(\left(3\right)\) \(\left(1-3x\right)-2\left(3x-6\right)=-4x-5\)
\(\Leftrightarrow1-3x-6x+12=-4x-5\)
\(\Leftrightarrow-3x-6x+4x=-1-12-5\)
\(\Leftrightarrow-5x=-18\)
\(\Leftrightarrow x=\dfrac{18}{5}\)
\(\left(4\right)\) \(x\left(4x-3\right)-2x\left(2x-1\right)=5x-7\)
\(\Leftrightarrow4x^2-3x-4x^2+2x=5x-7\)
\(\Leftrightarrow-x-5x=-7\)
\(\Leftrightarrow-6x=-7\)
\(\Leftrightarrow x=\dfrac{7}{6}\)
\(\left(5\right)\) \(3x\left(2x-1\right)-6x\left(x+2\right)=-3x+4\)
\(\Leftrightarrow6x^2-3x-6x^2-12x=-3x+4\)
\(\Leftrightarrow-15x+3x=4\)
\(\Leftrightarrow-12x=4\)
\(\Leftrightarrow x=-\dfrac{1}{3}\)
24 tháng 7 2019
a) \(\left(4x^2-2\right)^2=\frac{196}{81}\)
<=> \(2^2\left(2x^2-1\right)^2=\frac{196}{81}\)
<=> \(4\left(2x^2-1\right)^2=\frac{196}{81}\)
<=> \(\left(2x^2-1\right)^2=\frac{196}{81}:4\)
<=> \(\left(2x^2-1\right)^2=\frac{49}{81}\)
<=> \(2x^2-1=\pm\sqrt{\frac{49}{81}}\)
<=> \(2x^2-1=\pm\frac{7}{9}\)
<=> \(\orbr{\begin{cases}2x^2-1=\frac{7}{9}\\2x^2-1=-\frac{7}{9}\end{cases}}\)<=> \(\orbr{\begin{cases}x=\pm\frac{2\sqrt{2}}{3}\\x=\pm\frac{1}{3}\end{cases}}\)
=> \(\orbr{\begin{cases}x=\pm\frac{2\sqrt{2}}{3}\\x=\pm\frac{1}{3}\end{cases}}\)
TH
1
#)Góp ý :
Bạn ghi thiếu đề phải không ? (12x-5)(4x-1)+(3x-7)(1-16x) = 81
#)Giải :
\(\left(12x-5\right)\left(4x-1\right)+\left(3x-7\right)\left(1-16x\right)=81\)
\(\Leftrightarrow12x\left(4x-1\right)-5\left(4x-1\right)+3x\left(1-16x\right)-7\left(1-16x\right)=81\)
\(\Leftrightarrow12x.4x-12x-20x+5-3x+3x.16x-7+7.16x=81\)
\(\Leftrightarrow48x^2-12x-12x-20+5+3x-48x^2-7+112x=81\)
\(\Leftrightarrow\left(48x^2-48x^2\right)+\left(112x-12x-20x+3x\right)-\left(7-5\right)=81\)
\(\Leftrightarrow83x=81+2\)
\(\Leftrightarrow x=1\)