Question 130984
XY=90 OR Y=90/X
2X+2Y=40 NOW REPLACE Y WITH(90/X)
2X+2(90/X)=40
2X+180/X=40
(2X^2+180)/X=40
2X^2+180=40X
2X^2-40X+180=0
2(X^2-20X+90)=0
USING THE QUADRATIC EQUATION WE GET:
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}
X=(20+-SQRT[-20^2-4*1*90])/2*1
X=(20+-SQRT[400-360])/2
X=(20+-SQRT40)/2
X=(20+-6.32)/2
X=(20+6.32)/2
X=26.32/2
X=13.16 ANSWER.
X=(20-6.32)/2
X=13.68/2
X=6.84 ANSWER.