Answer:
0
Step-by-step explanation:
Given
- (x + [tex]\sqrt{1 + x^2}[/tex])(y + [tex]\sqrt{1 + y^2}[/tex]) = 1
- (x+y)² = ?
Solution
Let's make substitution as:
- (x + [tex]\sqrt{1 + x^2}[/tex]) = m
then
- (y + [tex]\sqrt{1 + y^2}[/tex]) = 1/m
Solving the first equation for x and the second one for y:
- (x + [tex]\sqrt{1 + x^2}[/tex]) = m
- [tex]\sqrt{1 + x^2}[/tex] = m - x
- 1 + x² = (m - x)²
- 1 + x² = m² - 2mx + x²
- 2mx = m² - 1
- x = (m² - 1)/2m
And
- (y + [tex]\sqrt{1 + y^2}[/tex]) = 1/m
- [tex]\sqrt{1 + y^2}[/tex] = 1/m - y
- 1 + y² = 1/m² -2y/m + y²
- 1 = 1/m² - 2y/m
- m² = 1 - 2my
- 2my = 1 - m²
- y = (1 - m²)/2m
- y = - (m² - 1)/2m
Now, sum of x and y:
- x + y = (m² - 1)/2m - (m² - 1)/2m = 0
Therefore:
Answer is zero