Question 470950
Solve the following application problem. Show and explain the variable equation used and each each step involved in solving the equation. 
The width of a rectangle is 4 cm less than its length. If the area of the rectange is 87 cm^2, find the dimensions of the rectangle to the nearest thousandth. 
**
let x=length of rectangle
x-4 =width of rectangle
area of rectangle=length*width=87 cm ^2
x(x-4)=87
x^2-4x-87=0
solve by quadratic formula as follows:
..
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}
..
a=1, b=-4, c=-87
x=[-(-4)ħsqrt((-4)^2-(4*1*(-87)]/2*1
x=[4ħsqrt(16+348)]/2
x=(4ħ√364)/2
x=(4ħ19.079)/2
x=11.539
x-4=7.539
or
x=-7.534 (reject, length>0)

ans:
length of rectangle=11.539 cm
width of rectangle=7.539 cm