What is the positive solution to the equation 0 = -x2 + 2x + 1?
Solution:
Given that –x2 + 2x + 1 = 0
⇒ Multiplying by -1 on both sides, we get x2 - 2x - 1 = 0
The quadratic formula is given by x = (-b ± √ (b2 - 4ac)) / 2
As we know that coefficient of x2 is a, coefficient of x is b and the constant term is c.
So, a = 1, b = - 2 and c = - 1
Using the quadratic formula, we get,
⇒ x = - (-2) ± √ ((- 2)2 - 4 (1) (-1)) / 2 (1)
⇒ x = - (-2) ± √ (4 + 4) / 2
⇒ x = - (-2) ± √ (8) / 2
On finding the square root, we will have two values of 'x'.
⇒ x = (2 + 2√2) / 2 or x = (2 - 2√2) / 2
⇒ x = 1 + √2 or x = 1 - √2
Hence, we see that 1 + √2 = 1 + 1.414 = 2.414, which is positive and 1 - √2 = 1 - 1.414 = -0.414, which is negative.
Thus, the positive solution to the equation –x2 + 2x + 1 = 0 is x = 1 + √2.
What is the positive solution to the equation 0 = -x2 + 2x + 1?
Summary:
The positive solution to the equation 0 = -x2 + 2x + 1 is x = 1 + √2.
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