Question

\(\sqrt{5x^2-2x+1}=4x\)

Answer 1

\(\sqrt{5x^2-2x+1}=4x\)

ĐK: x \(\ge\) 0

<=> 5x² - 2x + 1 = 16x²

<=> (x - 1)² + 4x² = 16x²

<=> (x - 1)² = 12x²

<=>(x - 1)² - 12x² = 0

<=> (x - 1 - \(\sqrt{12}x\))(x - 1 + \(\sqrt{12}x\)) = 0

<=> (x - 1 - \(\sqrt{12}x\)) = 0 hoặc (x - 1 + \(\sqrt{12}x\)) = 0

1) x - 1 - \(\sqrt{12}x\) = 0 <=> x \(\approx\) -0,406 (loại)

2) x - 1 + \(\sqrt{12}x\) = 0 <=> x \(\approx\) 0,224

Vậy: x \(\approx\) 0,224

Answer 2

\(x=0,22\)