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a)\(\left(x^2+1\right)\left(x^2-4x+4\right)=0\Leftrightarrow\orbr{\begin{cases}x^2+1=0\\x^2-4x+4=0\end{cases}\Rightarrow\orbr{\begin{cases}x^2=-1\left(vn\right)\\\left(x-2\right)^2=0\end{cases}\Rightarrow}x=2}\)
b)\(\left(3x-2\right)\left(\frac{2x+6}{7}-\frac{4x-3}{5}\right)=0\\ \Rightarrow\left(3x-2\right)\left(\frac{10x+30-28x+21}{35}\right)=0\)
\(\Rightarrow\left(3x-2\right)\left(\frac{-18x+51}{35}\right)=0\Rightarrow\orbr{\begin{cases}x=\frac{2}{3}\\x=\frac{17}{6}\end{cases}}\)
c)\(\left(3,3-11x\right)\left(\frac{21x+6+10-30x}{15}\right)=0\Leftrightarrow\orbr{\begin{cases}x=\frac{3}{10}\\x=\frac{16}{9}\end{cases}}\)
a) \(\left(4x-10\right)\left(24+5x\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}4x-10=0\\24+5x=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\dfrac{10}{4}=\dfrac{5}{2}\\x=-\dfrac{24}{5}\end{matrix}\right.\)
Vậy \(S=\left\{-\dfrac{24}{5};\dfrac{5}{2}\right\}\)
b) \(\left(3.5-7x\right)\left(0.1x+2.3\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}3.5-7x=0\\0.1x+2.3=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\dfrac{3.5}{7}=\dfrac{1}{2}\\x=-\dfrac{2.3}{0.1}=-23\end{matrix}\right.\)
Vậy \(S=\left\{-23;\dfrac{1}{2}\right\}\)
a) \(\left(x+3\right)\left(x^2-3x+9\right)-x\left(x-2\right)\left(x+2\right)=27\)
\(\Rightarrow x^3+3^3-x\left(x^2-4\right)=27\)
\(\Rightarrow x^3+27-x^3+4x=27\)
\(\Rightarrow27+4x=27\)
\(\Rightarrow4x=0\)
\(\Rightarrow x=0\)
b) \(2x^2+7x+3=0\)
\(\Rightarrow2x^2+x+6x+3=0\)
\(\Rightarrow x\left(2x+1\right)+3\left(2x+1\right)=0\)
\(\Rightarrow\left(2x+1\right)\left(x+3\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}2x+1=0\\x+3=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}2x=-1\\x=-3\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=-\dfrac{1}{2}\\x=-3\end{matrix}\right.\)
\(\left(x-1\right)^2-1+x^2=\left(1-x\right)\left(x+3\right)\)
\(\Leftrightarrow\left(x-1\right)^2+\left(x-1\right)\left(x+1\right)=\left(1-x\right)\left(x+3\right)\)
\(\Leftrightarrow2x\left(x-1\right)=\left(1-x\right)\left(x+3\right)\)
\(\Leftrightarrow2x\left(x-1\right)+\left(x-1\right)\left(x+3\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(3x+3\right)=0\)
\(\Rightarrow x=\pm1\)
Giúp tớ mấy câu còn lại đi các cậu, tớ cần gấp lắm ạ ;;-;;
Ta có : (x + 1)(x + 2)(x + 3)(x + 4) = 3x2
=> [(x + 1)(x + 4)][(x + 2)(x + 3)] = 3x2
=> (x2 + 5x + 4) (x2 + 5x + 6) = 3x2
Đặt x2 + 5x + 5 = a
Thay vào biểu thức ta có : (a - 1)(a + 1) = 3x2
<=> a2 - 1 = 3a2
<=> (x2 + 5x + 5)2 = 3x2
<=> x4 + 10x2 + 15 = 3x2
=> x4 + 10x2 + 15 - 3x2 = 0
<=> x4 + 7x2 + 15 = 0
<=> (x2 + 3,5)2 + 2,75 = 0
=> sai đề
a) đặt \(\left(x^2+x\right)\)là \(y\)
ta có: \(3y^2-7y+4\)\(=0\)
<=>\(\left(3y-4\right)\left(y-1\right)=0\)
còn lại bạn tự xử nhé
a)(2x+1)(3x-2)=(5x-8)(2x+1)
⇔(2x+1)(3x-2)-(5x-8)(2x+1)=0
⇔(2x+1)(3x-2-5x+8)=0
⇔(2x+1)(-2x+6)=0
⇔2x+1=0 hoặc -2x+6=0
1.2x+1=0⇔2x=-1⇔x=-1/2
2.-2x+6=0⇔-2x=-6⇔x=3
phương trình có 2 nghiệm x=-1/2 và x=3
\(a.\left(x^2+3x+2\right)\left(x^2+11x+30\right)-60=0\)
\(\Leftrightarrow\left(x^2+7x-4x+16-14\right)\left(x^2+7x+4x+16+14\right)-60=0\)
\(\Leftrightarrow\left(x^2+7x+16-4x-14\right)\left(x^2+7x+16+4x+14\right)=0\)
\(\Leftrightarrow\left(x^2+7x+16\right)^2-\left(4x+14\right)^2-60=0\)
Vì \(\left(x^2+7x+16\right)^2>0;\left(4x+14\right)^2>0\)
Nên \(\left(x^2+7x+16\right)^2-\left(4x+14\right)^2-60\ge-60\)
V...\(S=\varnothing\)
\(b.4^x-12.2^x+32=0\)
\(\Leftrightarrow\left(2^x\right)^2-2.2^x.6+36-4=0\)
\(\Leftrightarrow\left(2^x-6\right)^2-4=0\)
\(\Leftrightarrow\left(2^x-4\right)\left(2^x-8\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}2^x-4=0\\2^x-8=0\end{cases}\Leftrightarrow\orbr{\begin{cases}2^x=4\\2^x=8\end{cases}\Leftrightarrow}\orbr{\begin{cases}2^x=2^2\\2^x=2^3\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=2\\x=3\end{cases}}}\)
V...\(S=\left\{2;3\right\}\)
^^ đúng ko ta
a) (x+1)(x+2)(x+5)(x+6)-60=0
[(x+1)(x+6)][(x+2)(x+5)]-60=0
(x^2 + 7x + 6)(x^2 + 7x + 10) - 60 = 0
đặt t = x^2 + 7x + 8
pt trở thành
(t-2)(t+2)-60=0
t^2 - 64=0 .....
t=8 hoặc t=-8.
tìm x ....