To solve the quadratic equation x² + 8x + 5 = 0 by completing the square, follow these steps:
- Start with the original equation:
- Move the constant to the other side of the equation:
- To complete the square, take the coefficient of x (which is 8), divide it by 2, and square it:
- Add this square to both sides of the equation:
x² + 8x + 5 = 0
x² + 8x = -5
(8 / 2)² = 4² = 16
x² + 8x + 16 = -5 + 16
This simplifies to:
x² + 8x + 16 = 11
Now, the left side can be factored as a perfect square:
(x + 4)² = 11
- Take the square root of both sides:
- Now, solve for x by isolating the variable:
x + 4 = ±√11
x = -4 ± √11
Thus, the solutions are:
x = -4 + √11 and x = -4 – √11.