Giải phương trình
a)(x2 + 3x + 2)(x2 + 7x + 12) = 24
b)\(\frac{x^2}{\left(x+2\right)^2}=3x^2-6x-3\)
K
Khách
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Những câu hỏi liên quan
30 tháng 1 2018
a) \(2x^3 + 6x^2 = x^2 +3x\)
\(\Leftrightarrow2x^2\left(x+3\right)=x\left(x+3\right)\)
\(\Leftrightarrow2x^2\left(x+3\right)-x\left(x+3\right)=0\)
\(\Leftrightarrow\left(x+3\right)\left(2x^2-x\right)=0\)
\(\Leftrightarrow\left(x+3\right).x\left(2x-1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x+3=0\\x=0\\2x-1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-3\\x=0\\x=\dfrac{1}{2}\end{matrix}\right.\)
S = \(\left\{-3;0;\dfrac{1}{2}\right\}\)
b) \((3x-1) (x^2 +2 ) = (3x-1) (7x - 10)\)
\(\Leftrightarrow\left(3x-1\right)\left(x^2+2\right)-\left(3x-1\right)\left(7x-10\right)=0\)
\(\Leftrightarrow\left(3x-1\right)\left(x^2+2-7x+10\right)=0\)
\(\Leftrightarrow\left(3x-1\right)\left(x^2-7x+12\right)=0\)
\(\Leftrightarrow\left(3x-1\right)\left(x-3\right)\left(x-4\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}3x-1=0\\x-3=0\\x-4=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{3}\\x=3\\x=4\end{matrix}\right.\)
S = \(\left\{\dfrac{1}{3};3;4\right\}\)
CC
4
29 tháng 12 2017
\(\Leftrightarrow\left(x+1\right)\left(x+2\right)\left(x+3\right)\left(x+4\right)=24\)
\(\Leftrightarrow\left[\left(x+1\right)\left(x+4\right)\right]\left[\left(x+2\right)\left(x+3\right)\right]=24\)
\(\Leftrightarrow\left(x^2+5x+4\right)\left(x^2+5x+6\right)=24\)
\(\Leftrightarrow\left(x^2+5x+5\right)^2-1=24\)
\(\Leftrightarrow\left(x^2+5x+5\right)^2=25\)
Mà \(x^2+5x+5>0\forall x\)
\(\Rightarrow x^2+5x+5=5\Rightarrow x\left(x+5\right)=0\Rightarrow\orbr{\begin{cases}x=0\\x=-5\end{cases}}\)
Vậy pt có tập nghiệm S={0,-5}
29 tháng 12 2017
pt <=> (x+1).(x+2).(x+3).(x+4) = 24
<=> [(x+1).(x+4)].[(x+2).(x+3)] = 24
<=> (x^2+5x+4).(x^2+5x+6) = 24
<=> (x^2+5x+5)^2-1 = 24
<=> (x^2+5x+5) = 25
=> x^2+5x+5 = 5 [ vì x^2+5x+5 = (x+2,5)^2-0,25 >= -0,25 > -5 ]
=> x=0 hoặc x=-5
Vậy pt có tập nghiệm S = {-5;0}
k mk nha
3 tháng 5 2017
\(\frac{x+\frac{2\left(3-x\right)}{5}}{14}-\frac{5x-4\left(x-1\right)}{24}=\frac{7x+2+\frac{9-3x}{5}}{12}+\frac{2}{3}\)
\(\Leftrightarrow\frac{\frac{5x+6-2x}{5}}{14}-\frac{x+4}{24}=\frac{\frac{35x+10+9-3x}{5}}{12}+\frac{2}{3}\)
\(\Leftrightarrow\frac{\frac{3x+6}{5}}{14}-\frac{x+4}{24}=\frac{\frac{32x+19}{5}}{12}+\frac{2}{3}\)
\(\Leftrightarrow\left(\frac{3x+6}{5}\cdot\frac{1}{14}\right)-\frac{x+4}{24}=\left(\frac{32x+19}{5}\cdot\frac{1}{12}\right)+\frac{2}{3}\)(CHIA CHO 14 LÀ NHÂN NGHỊCH ĐẢO VỚI 1/14,) (CHIA CHO 12 LÀ NHÂN NGHỊCH ĐẢO VỚI 1/12)\(\Leftrightarrow\frac{3x+6}{70}-\frac{x+4}{24}-\frac{32x+19}{60}-\frac{2}{3}=0\)\(\Leftrightarrow\frac{12\left(3x+6\right)-35\left(x+4\right)-14\left(32x+19\right)-2\cdot280}{840}=0\)
\(\Leftrightarrow12\left(3x+6\right)-35\left(x+4\right)-14\left(32x+19\right)-560=0\)
\(\Leftrightarrow36x+72-35x-140-448x-266-560=0\)
\(\Leftrightarrow-447x-894=0\Leftrightarrow x=\frac{-894}{447}=-2\)(NHẬN)
Vậy tập nghiệm của phương trình là : S = { -2 }
tk cho mk nka ! ! ! th@nks ! ! !
HP
11 tháng 1 2022
\(a.\left(3x+2\right)\left(x^2-1\right)=\left(9x^2-4\right)\left(x+1\right)\)
\(\Leftrightarrow\left(3x+2\right)\left(x+1\right)\left(x-1\right)=\left(3x-2\right)\left(3x+2\right)\left(x+1\right)\)
\(\Leftrightarrow x-1=3x-2\)
\(\Leftrightarrow2x=1\)
\(\Leftrightarrow x=\dfrac{1}{2}\)
11 tháng 1 2022
c: =>x-3=0
hay x=3
d: \(\Leftrightarrow\left(3x-1\right)\cdot\left(x^2+2-7x+10\right)=0\)
\(\Leftrightarrow\left(3x-1\right)\left(x-3\right)\left(x-4\right)=0\)
hay \(x\in\left\{\dfrac{1}{3};3;4\right\}\)
11 tháng 1 2022
\(\left(3x+2\right)\left(x^2-1\right)=\left(9x^2-4\right)\left(x+1\right).\)
\(\Leftrightarrow\left(3x+2\right)\left(x-1\right)\left(x+1\right)-\left(3x-2\right)\left(3x+2\right)\left(x+1\right)=0.\)
\(\Leftrightarrow\left(3x+2\right)\left(x+1\right)\left(x-1-3x+2\right)=0.\)
\(\Leftrightarrow\left(3x+2\right)\left(x+1\right)\left(-2x+1\right)=0.\)
\(\Leftrightarrow\left[{}\begin{matrix}3x+2=0.\\x+1=0.\\-2x+1=0.\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{2}{3}.\\x=-1.\\x=\dfrac{1}{2}.\end{matrix}\right.\)
11 tháng 1 2022
c: =>(x-3)(x2+3x+5)=0
=>x-3=0
hay x=3
d: =>(3x-1)(x2+2-7x+10)=0
=>(3x-1)(x-3)(x-4)=0
hay \(x\in\left\{\dfrac{1}{3};3;4\right\}\)
a/ \(\Leftrightarrow\left(x+1\right)\left(x+2\right)\left(x+3\right)\left(x+4\right)=24\)
\(\Leftrightarrow\left(x^2+5x+4\right)\left(x^2+5x+6\right)-24=0\)
\(\Leftrightarrow\left(x^2+5x+4\right)^2+2\left(x^2+5x+4\right)-24=0\)
\(\Leftrightarrow\left(x^2+5x\right)\left(x^2+5x+10\right)=0\)
b/ ĐKXĐ; ...
\(\Leftrightarrow\frac{x^2}{x^2+4x+4}+12x+5=3x^2+6x+2\)
\(\Leftrightarrow\frac{x^2+\left(12x+5\right)\left(x^2+4x+4\right)}{x^2+4x+4}=3x^2+6x+2\)
\(\Leftrightarrow\frac{\left(4x+10\right)\left(3x^2+6x+2\right)}{x^2+4x+4}=3x^2+6x+2\)
\(\Leftrightarrow\left[{}\begin{matrix}3x^2+6x+2=0\\\frac{4x+10}{x^2+4x+4}=1\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}3x^2+6x+2=0\\x^2=6\end{matrix}\right.\)
a) Ta có :
(x2 + 3x + 2)(x2 + 7x + 12) = 24
⇔ ( x + 1 ) ( x + 2 ) (x + 3 ) ( x + 4 ) = 24
⇔ ( x + 1 ) ( x + 4 ) ( x + 2 ) ( x + 3 ) - 24 = 0
⇔ ( x2 + 5x + 4 ) ( x2 + 5x + 6 ) - 24 = 0
Đặt t = x2 + 5x + 4, ta có :
t ( t + 2 ) - 24 = 0
⇔ t2 + 2t +1 - 25 = 0
⇔ ( t + 1 )2 - 52 = 0
⇔ ( t - 4 ) ( t + 6 ) = 0
\(\Leftrightarrow\left[{}\begin{matrix}t-4=0\\t+6=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}t=4\\t=-6\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x^2+5x+4=4\\x^2+5x+4=-6\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x^2+5x=0\\x^2+5x+10=0\end{matrix}\right.\)
Sau đó tìm x bạn tự làm nha
Ý b) là - 3 à !?