Question

The breadth of a rectangle is 4cm less than its length. Its area is 21 square cm. Find the length of the rectangle in cm

Answer 1

Answer:

length = 7cm

Step-by-step explanation:

let the length of the rectangle be x cm

breadth of the rectangle =( x-4)cm

area = 21sq cm

$area = l \times b \\ 21 = x \times (x - 4) \\ 21 = {x}^{2} - 4x \\ {x}^{2} - 4x - 21 = 0 \\ {x}^{2} + 3x - 7x - 21 = 0 \\ x( x+ 3) - 7(x + 3) = 0 \\ (x + 3)(x - 7) = 0 \\ x = - 3 \: and \: 7$

rejecting negative values

x= 7

length = 7cm

breadth = 7-4 = 3cm