Answer:
x = 4 + 2 sqrt(5) or x = 4 - 2 sqrt(5)
thus :
8
Explanation:
Solve for x over the real numbers:
x^2 - 8 x - 4 = 0
Hint: | Solve the quadratic equation by completing the square.
Add 4 to both sides:
x^2 - 8 x = 4
Hint: | Take one half of the coefficient of x and square it, then add it to both sides.
Add 16 to both sides:
x^2 - 8 x + 16 = 20
Hint: | Factor the left hand side.
Write the left hand side as a square:
(x - 4)^2 = 20
Hint: | Eliminate the exponent on the left hand side.
Take the square root of both sides:
x - 4 = 2 sqrt(5) or x - 4 = -2 sqrt(5)
Hint: | Look at the first equation: Solve for x.
Add 4 to both sides:
x = 4 + 2 sqrt(5) or x - 4 = -2 sqrt(5)
Hint: | Look at the second equation: Solve for x.
Add 4 to both sides:
Answer: x = 4 + 2 sqrt(5) or x = 4 - 2 sqrt(5)