00:02
Here in this problem, the room is 12 feet by 15 feet, and the area of the rag is 108 square feet, and the rag is set in the room leaving, say, x feet, white border, and we have to find out the width of the border.
00:21
Now, if the border is x feet white, then, the length of the rug will be 12 minus 2x and the breadth of the rug will be 12 minus 2x.
01:02
And the breadth of the rug will be 15 minus 2x.
01:26
Now the area of the rag is 108 square feet.
01:30
So we can write 12 minus 2x times 15 minus 2x.
01:36
2x is equal to 108.
01:42
So 4x squared minus 54x plus 180 minus 108 is equal to 0.
01:58
So it is 4x square minus 54 x plus 72 is equal to 0.
02:05
So if we divide the whole equation both side by 2, we get 2x square minus 27 x plus 36 is equal to 0.
02:16
Now the coefficient of x square is 2 and this 1 36.
02:22
So altogether it is 72...