Question 374315
XY=96 OR X=90/Y
2X+2Y=40
REPLACING X IN THE SECOND EQUATION WITH (90/Y).
2(90/Y)+2Y=40
180/Y+2Y=40
(180+2Y*Y)/Y=40
(2Y^2+180)/Y=40 CROSS MULTIPLY.
2Y^2+180=40Y
2Y^2-40Y+180=0
2(Y^2-20Y+90)=0
{{{y = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}
y=(20+-sqrt[-20^2-4*1*90])/2*1
y=(20+-sqrt[400-360])/2
y=(20+-sqrt40)/2
y=(20+-6.325)/2
y=(20+6.325)/2
y=26.325/2
y=13.1625 ans.
x=90/13.1625
x=6.8376 ans.
Proof:
2*13.625+2*6.8376=40
26.325+13.675=40
40=40