Question 523729
width be x
length = 3x+5

Area = L*W

Area = x(3x+5)
3x^2+5x=42
3x^2+5x-42=0
a=	3	,b=	5	,c=	-42
					
b^2-4ac=	25	+	504		
b^2-4ac=	529				
{{{x=(-b+-sqrt(b^2-4ac))/(2a)}}}					
{{{x1=(-b+sqrt(b^2-4ac))/(2a)}}}					
{{{x1=(-12+21)/(12)}}}					
x1=(	-5	+	23	)/	6
x1=	3	      			
x2=(	-5	-23	) /	6	
x2= 	-4.67	
ignore negative value
width = 3 cm
length =>3x+5=>3*3+5= 14 cm