SOLUTION: If x + y = 11 and y = 15/x, find the value of x^2 + y^2.

Question 256387: If x + y = 11 and y = 15/x, find the value of x^2 + y^2.
Found 2 solutions by Edwin McCravy, jim_thompson5910:
Answer by Edwin McCravy(20056) (Show Source): You can put this solution on YOUR website!
If and , find the value of .

square both sides: Take the other equation Multiply both sides by x Substitute for in Edwin

Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
One way you could do it is to explicitly solve for both x and y and then just add their squares. However, here's another way to do this problem.

Start with the second equation.

Multiply both sides by x.

Multiply both sides by 2.

Move back to the first equation.

Square both sides

Square 11 to get 121

FOIL

Plug in (this is why I manipulated the second equation)

Subtract 30 from both sides.

Subtract

So the solution is
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