x = ±2.12 - 2. Solving the quadratic equation 2x²+8x-1=0 by using completing the square, we obtain the roots x = 0.12 and x = -4.12.
We can solve the quadratic equation 2x²+8x-1=0 by completing the square follow the next steps:
Divide the coefficients of the equation by a (the coefficient x²)
(2x²+8x-1)/2=0 -----> x²+4x-1/2=0
Move the independent term c/a to the right side of the equation
x²+4x = 1/2
Complete the square on the left side of the equation and balance this by adding the same number to the right side of the equation using (b/2)².
(b/2)²=(4/2)²=2²=4
x²+4x+4 = 1/2+4 -------> (x+2)² = 9/2
Applying square root on both sides of the equation
x+2 = √9/2
Finally, clear the x
x = √9/2 - 2 ----------> x = ±2.12132 - 2
Correct to 2 decimal places
x = ± 2.12 - 2
