\(x\left(3x-4\right)=2x^2+1\)
\(\Leftrightarrow3x^2-4x-2x^2-1=0\)
\(\Leftrightarrow x^2-4x-1=0\)
Theo Vi - ét, ta có :
\(\left\{{}\begin{matrix}x_1+x_2=-\dfrac{b}{a}=4\\x_1x_2=\dfrac{c}{a}=-1\end{matrix}\right.\)
Ta có :
\(A=x_1^2+x_2^2+3x_1x_2\)
\(=\left(x_1+x_2\right)^2-2x_1x_2+3x_1x_2\)
\(=\left(x_1+x_2\right)^2+x_1x_2\)
\(=4^2-1\)
\(=16-1\)
\(=15\)
2x2 mu 2-6x-1=0 A= x1-2 phan x2-1 + x2-2 phan x1-1 Giup mk nhe
5x mu 2 -7x+1=0 A= (x1-7/5)x1+1/25x2 mu 2 + x2 mu 2 Giup mk nhe
cho pt X^2-(2m+4)X+1=0
Tìm min A=(X1-2X2)(X1-X2)
Cho pt 2x2 +3x --1 =0 có 2 nghiệm x1, x2
Tính B= (4x1-1)/x2 + (4x2-1)/x1
(x1-x2)mu 2 -x1(x1-1/2)
3. Cho pt : x^2 + x + 2m - 4 =0 M ? pt có 2No p biệt x1 , x2 t/m : x^2 1= 2x2 + 5
5. Cho pt : 2x2 - (2m + 1 ) . x -4m - 5 = 0 m? Để pt x1 , x2 trái dấu t/m x1 = 2 |x2|
Pt: x^2-2x- căn 3 +1=0 A= x1^2x2^2 -2x1x2-x1-x2 Giúp tớ nhaaaa cmon ạ
