what does an answer of {} mean?

when I type solve(x,y,xy=76,a+b=18), I get {} as an answer.

Guest Oct 4, 2017

#1**+2 **

You have 4 variables but only 2 equations....we can't derive any solutions from this

{ } means no solutions exist

Are you sure this isn't meant to be

xy = 76 and x + y = 18 ???

If so....... xy = 76 ⇒ y = 76/x

Putting this into the second equation, we have

x + 76/x = 18 multiply through by x

x^2 + 76 =18x rearrange as

x^2 - 18x + 76 = 0

The two solutions are x = 9 - √5 and x = 9 + √5

Whichever you choose for x, y will be the other one

CPhill Oct 4, 2017