If x+y=-10, and x=25/y, what is the value of x^2+y^2?  Choose the most appropriate option: A) 55 B) 65 C) 50 D) 75 E) 85
x^2 + y^2 should make you think of these formulas:   (x+y)(x+y) = x^2+y^2+2xy   We already know (x+y) = -10 and x*y = 25   (x+y)(x+y) = (-10)(-10) = x^2+y^2+2*(25)   x^2+y^2 = 100 - 50= 
<gadget id="calculator">100 - 50</gadget>
<output>50</output>
50   Answer : 50
<result>C</result>
If x+y=-10, and x=25/y, what is the value of x^2+y^2?