Question

[xxx]

tìm x:

a) ( x + 5) ( x-1) - ( x-5) ( x-2) =0

b) ( x-3) (x+7) - ( x-2) ( x+4) = 0

c) ( x- 6) (x-7) - x( x+4) -5(x-1) = 0

Answer 1

[Akai Haruma]

Lời giải:

a)

PT $\Leftrightarrow (x^2+4x-5)-(x^2-7x+10)=0$

$\Leftrightarrow 11x-15=0$

$\Leftrightarrow x=\frac{15}{11}$

b)

PT $\Leftrightarrow (x^2+4x-21)-(x^2+2x-8)=0$

$\Leftrightarrow 2x-13=0$

$x=\frac{13}{2}$

c)

PT $\Leftrightarrow (x^2-13x+42)-(x^2+4x)-(5x-5)=0$

$\Leftrightarrow -22x+47=0\Rightarrow x=\frac{47}{22}$