Question

the area of a rectangular field is x^2-x-72 m^2. The length of the field is x+8 cm. What is the width of the field meters.

Answer 1

Hello,


A(x)=x²-x-72 (m²)
L=(x+8) (cm)= (x+8)/100 (m)

We suppose here x≠-8
(in reality x²-x-72>0 ==>x<-8 or x>9
but x+8>0 ==> x>-8
 then
only x>9 are solutions)

W=A(x)/ ((x+8)/100 )=100*(x²-x-72)/(x+8)= 100*(x-9)(x+8)/(x+8)=100*(x-9)