Question

the perimeter of a rectangular plot is 180 and area is 1800 m square take the length of the plot as x metre use the perimeter vanity me to write the value of breath in terms of use the value of length breadth and area to write an equation in next solve the equation to calculate the length and breadth of the plot

Answer 1

if 2(l+b) = 180
l+b = 90
lb =1800
l = 90-b
(90-b)b = 1800
90b-b2 = 1800
-b2 +90b -1800 = 0
Step-3 : Rewrite the polynomial splitting the middle term using the two factors found in step 2 above,  -60  and  -30 
                     b2 - 60b - 30b - 1800

Step-4 : Add up the first 2 terms, pulling out like factors :
                    b • (b-60)
              Add up the last 2 terms, pulling out common factors :
                    30 • (b-60)
Step-5 : Add up the four terms of step 4 :
                    (b-30)  •  (b-60)
then b= 30 or b= 60
then l = 60 or 30