Question

The area of a rectangular lot is (12x² + 17x – 40) m². If the width is (4x – 5) m, find the perimeter of the lot.

Answer 1

Answer:

perimeter of plot =12x² + 17x – 40) m²

width =   (4x – 5) m

let  length =  x

so , 2(l + b) = 12x² + 17x – 40) m²

2 (x + {4x -5}m )  = 12x² + 17x – 40) m²

  5x - 5 m       =  12x² + 17x – 40) m²/2 =

Answer 2

Perimeter of the rectangle lot = (14x+6) m

Given:

The area of a rectangular lot is (12x² + 17x – 40) m²

And the width of the lot =  (4x – 5) m

To find:

Perimeter of the lot

Solution:

Given area of a rectangular = (12x² + 17x – 40) m²

factorize the (12x² + 17x – 40)  

⇒ 12x² + 17x - 40

⇒ 12x² -15x +32x - 40

⇒ 3x(4x -5) + 8(4x -5)

⇒ (4x -5) (3x+8)

Given that area of plot = (12x² + 17x – 40) m²

As we know area of rectangle = length × width

⇒ length × width  = (12x² + 17x – 40)

From above data

⇒ length × (4x – 5) = (4x -5) (3x+8)

⇒ length of the plot = (3x+8)

Perimeter of rectangle = 2(length + breadth)

= 2(3x+8 + 4x – 5)

= 2(7x +3) =14x +6  

Perimeter of the rectangle lot = (14x+6) m

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