3x² -13x +4 = 0

<=>3x² -x -12x +4 = 0

<=> x( 3x-1) -4 (3x-1) = 0

<=> (x-4)(3x-1)=0

Vậy x =4 hoặc x =1/3

\(F=x^2-6x+8=0\)\(\Leftrightarrow\left(x^2-2x\right)-\left(4x-8\right)=0\Leftrightarrow x\left(x-2\right)-4\left(x-2\right)=0\Leftrightarrow\left(x-2\right)\left(x-4\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x=2\\x=4\end{cases}}\)

\(G=2x^2+3x+1=0\)

\(\Leftrightarrow\left(2x^2+2x\right)+\left(x+1\right)=0\Leftrightarrow2x\left(x+1\right)+\left(x+1\right)=0\Leftrightarrow\left(x+1\right)\left(2x+1\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x=-1\\x=-\frac{1}{2}\end{cases}}\)

\(C=x^2-7x+12=0\)

\(\Leftrightarrow\left(x^2-3x\right)-\left(4x-12\right)=0\Leftrightarrow x\left(x-3\right)-4\left(x-3\right)=0\Leftrightarrow\left(x-3\right)\cdot\left(x-4\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x=3\\x=4\end{cases}}\)

\(E=x^2+13x+36=0\)

\(\Leftrightarrow\left(x^2+9x\right)+\left(4x+36\right)=0\Leftrightarrow x\left(x+9\right)+4\left(x+9\right)=0\Leftrightarrow\left(x+9\right)\left(x+4\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x=-9\\x=-4\end{cases}}\)

bạn tự kết luận nha

có chỗ nào trình bày chưa được hoặc sai nhớ chỉ mình nhé (thanks a lot)

Đặt D(x)=0

\(\Leftrightarrow2x^2-13x+15=0\)

\(\Leftrightarrow2x^2-3x-10x+15=0\)

=>(2x-3)(x-5)=0

=>x=3/2 hoặc x=5

=> 6x² - 3x + 16x - 8 =0                                                                                                                                                                                               => 3x(2x - 1) + 8(2x - 1) =0                                                                                                                                                                                       => (3x + 8)(2x - 1)  =0                                                                                                                                                                                            => 3x+8 =0 => x=-8/3  và 2x-1=0 => x=-1/2                                                                                                                                                                                              

\(6x^2+13x-8=0\)

\(\Leftrightarrow6x^2+16x-3x-8=0\)

\(\Leftrightarrow6x\left(x+\frac{8}{3}\right)-3\left(x+\frac{8}{3}\right)=0\)

\(\Leftrightarrow\left(x+\frac{8}{3}\right)\left(6x-3\right)=0\)

Ra phương trình tích rồi, bạn cho từng cái = 0 và giải ra tìm x nhé

F = x² - 6x + 8 =0

x² - 2x - 4x + 8 = 0

x . (x - 2) - 4 . (x - 2) = 0

(x - 4).(x - 2) = 0

=> x - 4 = 0 <=> x = 4

x - 2 = 0 <=> x = 2

b: G(x)=0

\(\Leftrightarrow2x^2+3x+1=0\)

\(\Leftrightarrow\left(2x+1\right)\left(x+1\right)=0\)

=>x=-1 hoặc x=-1/2

c: C(x)=0

\(\Leftrightarrow x^2-7x+12=0\)

\(\Leftrightarrow\left(x-3\right)\left(x-4\right)=0\)

=>x=3 hoặc x=4

d: E(x)=0

\(\Leftrightarrow x^2+13x+36=0\)

\(\Leftrightarrow\left(x+9\right)\left(x+4\right)=0\)

=>x=-9 hoặc x=-4

câu a và b mk bt lm r, các bn giúp mk câu c nha

1) \(f\left(x\right)=6x^2-15x+4\)

\(\Rightarrow f\left(x\right)=6\left(x^2-\dfrac{5}{3}x\right)+4\)

\(\Rightarrow f\left(x\right)=6\left(x^2-\dfrac{5}{3}x+\dfrac{25}{36}-\dfrac{25}{36}\right)+4\)

\(\Rightarrow f\left(x\right)=6\left(x^2-\dfrac{5}{3}x+\dfrac{25}{36}\right)+4-\dfrac{25}{6}\)

\(\Rightarrow f\left(x\right)=6\left(x-\dfrac{5}{6}\right)^2-\dfrac{1}{6}\ge-\dfrac{1}{6}\left(6\left(x-\dfrac{5}{6}\right)^2\ge0,\forall x\right)\)

\(\Rightarrow GTNN\left(f\left(x\right)\right)=-\dfrac{1}{6}\left(tạix=\dfrac{5}{6}\right)\)

2) \(f\left(x\right)=4x^2-13x+5\)

\(\Rightarrow f\left(x\right)=4\left(x^2-\dfrac{13}{4}x\right)+5\)

\(\Rightarrow f\left(x\right)=4\left(x^2-\dfrac{13}{4}x+\dfrac{169}{64}-\dfrac{169}{64}\right)+5\)

\(\Rightarrow f\left(x\right)=4\left(x^2-\dfrac{13}{4}x+\dfrac{169}{64}\right)+5-\dfrac{169}{16}\)

\(\Rightarrow f\left(x\right)=4\left(x-\dfrac{13}{8}\right)^2-\dfrac{89}{16}\ge-\dfrac{89}{16}\left(4\left(x-\dfrac{13}{8}\right)^2\ge0,\forall x\right)\)

\(\Rightarrow GTNN\left(f\left(x\right)\right)=-\dfrac{89}{16}\left(tạix=\dfrac{13}{8}\right)\)

13x – 26 = 0

        13x = 26

            x = 26:13

            x = 2