Question

(8x - 3)(3x + 2) - (4x + 7 )(x + 4) = (2x + 1)(5x - 1)

Help mình với mn

Answer 1

(8x- 3)(3x+2) - (4x+7)(x+4)= (2x+1)(5x-1)
<=> (8x- 3).(3x+2) - (4x+7).(x+4)- (2x+1).(5x-1)=0
<=> 24x^2+16x- 9x- 6- 4x^2 - 16x -7x -28- 10x^2 +2x-5x+1=0
<=> 10x^2 -19x -33=0
<=> 10x^2+11x -30x -33=0
<=> x.(10x +11) - 3.(10x+11)=0
<=> (x-3).(10x+11) =0
<=> x-3=0 <=> x=3
Hoặc 10x+11=0 <=> x=-11/10. 

Sai thì xl ạ

Answer 2

(8x - 3)(3x + 2) - (4x + 7 )(x + 4) = (2x + 1)(5x - 1)

<=> 24x² + 16x - 9x - 6 - 4x² - 16x - 7x - 28 =  10x² + 3x -1

<=> 24x² + 16x - 9x - 6 - 4x² - 16x - 7x - 28  -  10x² - 3x + 1 = 0

<=> 10x² - 19x - 33 = 0

<=> 10x² - 30x + 11x - 33 = 0

<=> 10x (x -3) + 11(x-3) = 0

<=> (10x + 11)(x-3) = 0

<=>\(\left[{}\begin{matrix}10x+11=0\\x-3=0\end{matrix}\right.=>\left[{}\begin{matrix}x=\dfrac{-11}{10}\\x=3\end{matrix}\right.\)