Question

. Find the perimeter of a rectangular field whose length is four times its width and which has an area equal to 30976 cm2.

Answer 1

let the breadth of the rectangular field be x
so, the length will be 4x
area of rectangle = length*breadth
⇒ 30976 = x*4x
⇒30976 = 4x²
⇒30976/4 = x²
⇒7744 = x²
⇒88 = x
so length will be = 4x = 4*88 = 352 cm
perimeter of rectangle = 2(l+b)cm 
                                    ⇒ 2 (88+352)cm
                                    ⇒2*440 cm
                                    ⇒880 cm 
i hope this will help you

Answer 2

let the -
length breadth be x
length - 4x
 area of rectangle - 30976 cm²
formula for the area of rectangle - length*breadth
x*4x = 30976
x² = 30976 / 4
x² = 7744
x = 88
length is 4x - 4*88 = 352
∵length - 352
∵ breadth - 88
perimeter -
formula - 2(length + breadth)
2(88+352)
2(440)
880 cm
∵ perimeter is  880cm