Question

a)x(x+5)=x+5

b)x^2-1/9=0

c)(2x-3)^2-(x+5)^2=0

Answer 1

a) $x(x+5) = x+5 \Leftrightarrow (x-1)(x+5) = 0 \Leftrightarrow \left[\begin{aligned}&x = 1\\&x = -5\\ \end{aligned}\right.$;

b) $x^2 = \dfrac19 \Leftrightarrow x = \dfrac13$ hoặc $x = -\dfrac13$;

c) $(2x - 3)^2 - (x + 5)^2 = 0 \Leftrightarrow (2x - 3 - x - 5)(2x - 3 + x + 5) = 0 \Leftrightarrow (x - 8)(3x + 2) = 0 \Leftrightarrow \left[\begin{aligned}&x = 8\\&x = -\dfrac23\\ \end{aligned}\right.$.