Answer: width:60.2 cm
Length: 64.2 cm
Step-by-step explanation:
Given
The area of the rectangle is [tex]3990\ cm^2[/tex]
Width of the rectangle is [tex]x\ cm[/tex]
Length of the rectangle is [tex]x+4\ cm[/tex]
Area of the rectangle is the product of length and width
[tex]\therefore 3990=(x+4)x\\\Rightarrow 3990=x^2+4x\\\Rightarrow x^2+4x-3990=0\\\Rightarrow x=60.198\ or\ -65.198\ cm\\\text{Neglecting negative term}\\\Rightarrow x=60.198\approx 60.2\ cm[/tex]
Width of the rectangle is [tex]60.2\ cm[/tex]
Length of the rectangle is [tex]60.2+4=64.2\ cm[/tex]