Question 311835
W=2L-5
A=LW
140=L(2L-5)
140=2L^2-5L
2L^2-5L-140=0
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}} 
X=(5+-SQRT(-5^2-4*2*-140])/2*2
X=(5+-SQRT(25+1,120])/4
X=(5+-SQRT1,145)/4
X=(5+-33.8378)/4
X=(5+33.8378)/4
X=38.8378/4
X=9.7 ANS.
X=(5-33.8378)/4
X=-28.8378/4
X=-7.21 ANS.