the length of a rectangle exceeds its width by 12 inches and the area is 85 square inches. what are the length and width of the rectangle?

Respuesta :

If the length exceeds the width by 12, that only means that the length is 12 inches longer.  L = w + 12.  Width is just w.  To find the area we multiply length by width.  Since we have a value for the area, our equation looks like this: 85=(w+12)(w).  Distributing we have [tex]w^2+12w=85[/tex].  Bring that 85 over to the other side by subtraction and set the polynomial equal to 0 so we can factor it. [tex]w^2+12w-85=0[/tex].  We need to factor that to solve for w.  Plugging those numbers into the quadratic formula we get w values of 5 and -17.  We all know that the 2 things in math that will never EVER be negative are time and distance/length, so -17 is out.  The width then is 5.  The length is w + 12, so the length is 17.  There you go!