The length of a rectangle is 15 centimeters less than its width. What are the dimensions of the rectangle if its area is 100 square centimeters?
Let
x ----> length
y ----> width
Area of rectangle is
A=xy ------> equation 1
we have
x=y-15
A=100 cm2
substitute the given values in equation 1
100=(y-15)y
100=y^2-15y
y^2-15y-100=0
solve the quadratic equation by grahing
see the attached figure
the value of y=20 cm
Find the value of x
x=y-15
x=20-15=5 cm
therefore
the dimensions are
Length 5 cm
Width 20 cm