Question

Find the positive solution and please explain how ;4;

Answer 1

(x + 2)² - 10 = 0 (assuming it's equal to zero)

Expand the binomial: (x + y)² = x² + 2xy + y²
Thus, x² + 4x + 4 - 10 = 0
x² + 4x - 6 = 0

$x = \frac{-4 +_- \sqrt{16 + 24}}{2}$ (by quadratic formula)
$= \frac{-4 +_- \sqrt{40}}{2}$
$= \frac{-4 +_- 2\sqrt{10}}{2}$
$= -2 + \sqrt{10}$, since we're taking the positive solution.