Question

A rectangular playground is 420 sq.m. If its length is increased by 7 m and breadth is decreased by 5 meters the area remains the same Find the length of the playground ​

Answer 1

Answer:

Step-by-step explanation:

Answer 2

Step-by-step explanation:

let length be x metre and breadth be y metre

area of rectangular ground= area of rectangle

420=l b

420 =xy.................1

length is increased by 7m breadth is decreased by 5m

then area remain same

(X+7)(y-5)= 420

X(y-5)+7(y-5)=420

xy-5x+7y-35=420

420-5x+7y-35=420

-5x+7y-35=0

5x-7y+35=0

5x-7y= -35

-7y= -35-5x

y= -35-5x/-7

y= 35+5x/7

put y = 35+5x/7 in equation 1

420= X( 35+5x/7 )

420×7= 35x +5x2 .....2 means square

2940= 5x2 + 35x

5x2 +35x - 2940 = 0

devide whole equation by 5

X2 +35x -588=0

on solving

X= 28metre

y = 15 metre