Question

\(7\sqrt{x-3}-2\sqrt{4x-12}=12\)

Answer 1

  

Answer 2

ĐKXĐ: x ≥ 3

Phương trình tương đương:

7√(x - 3) - 2.2√(x - 3) = 12

⇔ 7√(x - 3) - 4√(x - 3) = 12

⇔ 3√(x - 3) = 12

⇔ √(x - 3) = 12 : 3

⇔ √(x - 3) = 4

⇒ x - 3 = 16

⇔ x = 16 + 3

⇔ x = 19 (nhận)

Vậy S = {19}

Answer 3

\(7\sqrt{x-3}-2\sqrt{4x-12}=12\\ \Leftrightarrow7\sqrt{x-3}-2\sqrt{4\left(x-3\right)}=12\\ \Leftrightarrow7\sqrt{x-3}-4\sqrt{x-3}=12\\ \Leftrightarrow3\sqrt{x-3}=12\\ \Leftrightarrow\sqrt{x-3}=\dfrac{12}{3}\\ \Leftrightarrow\sqrt{x-3}=4\\ \Leftrightarrow\left(\sqrt{x-3}\right)^2=4^2\\ \Leftrightarrow x-3=16\\ \Leftrightarrow x=16+3\\ \Leftrightarrow x=19.\)