Question

a) (2x+5)(x-3)=(x-4)(3-x)

b) 18x²(x+4)-12(x²+4x)=0

c) 16x²-10x+1=2(5x-1)(3x-4)

d) 3x²-6x+3=(x-1)(4x-5)

Answer 1

a) (2x + 5)(x - 3) = (x - 4)(3 - x)

<=> (2x + 5)(x - 3) + (x - 3)(x - 4) = 0

<=> (2x + 5 + x - 4)(x - 3) = 0

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

<=> \(\left[{}\begin{matrix}3x+1=0\\x-3=0\end{matrix}\right.\)

<=> \(\left[{}\begin{matrix}x=-\frac{1}{3}\\x=3\end{matrix}\right.\)

Vậy S = {-1/3; 3}

b) 18x²(x + 4) - 12(x² + 4x) = 0

<=> 18x²(x + 4) - 12x(x + 4) = 0

<=> 6x(x + 4)(3x - 2) = 0

<=> \(\left[{}\begin{matrix}x=0\\x+4=0\\3x-2=0\end{matrix}\right.\)

<=> \(\left[{}\begin{matrix}x=0\\x=-4\\x=\frac{2}{3}\end{matrix}\right.\)

Vậy S = {0; -2; 2/3}