Tìm x biết x – 3 = (3 - x)^2.
Giải thích
x – 3 = (3 - x)2
⇔ x – 3 = 9 – 6x + x2
⇔ x2 – 7x + 12 = 0
⇔ x2 – 3x – 4x + 12 = 0
⇔ x(x – 3) – 4(x – 3) = 0
⇔ (x – 3)(x – 4) = 0
⇔ x=3x=4
Vậy x = 3 hoặc x = 4.
x – 3 = (3 - x)2
⇔ x – 3 = 9 – 6x + x2
⇔ x2 – 7x + 12 = 0
⇔ x2 – 3x – 4x + 12 = 0
⇔ x(x – 3) – 4(x – 3) = 0
⇔ (x – 3)(x – 4) = 0
⇔ x=3x=4
Vậy x = 3 hoặc x = 4.