Question 205148
(11-2x)(14-2x)=80
154-28x-22x+4x^2=80
4x^2-50x+154-80=0
4x^2-50x+74=0
Using the quadratic equation {{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}} we get:
x=(50+-sqrt[-50^2-4*4*74])/2*4
x=(50+-sqrt[2,500-1,184])/8
x=(50+-sqrt1,316)/8
x=(50+-36.2767)/8
x=(86.2767)/8
x=10.78 not an ans.
x=(50-36.2767)/8
x=13.7233/8
x=1.7154 in. is the size of the square removed from the 4 corners.
Proof:
(11-2*1.7154)(14-2*1.7154)=80
(11-3.43)(14-3.43)=80
7.57*10.57=80
80~80