Question

If the area of a rectangle is 400 cm2 and its breadth is 16 cm, so the length of this rectangle is

Answer 1

Answer:

Given: Area of given rectangle = 21 square cm

Solution:

Let Length of one side of given rectangle = x cm; then

Length of second side of given rectangle = x + 4 cm

Formula for Area of rectangle = L X W

Put values in formula , we have

x . ( x + 4) = 21

=> x^2 + 4x = 21

=> x^2 + 4x - 21 = 0

=> x^2 + 7x - 3x - 21 = 0

=> x(x + 7) -3(x + 7) = 0

=> (x -3) (x + 7) = 0

=> x -3 = 0 or x + 7 = 0

=> x = 3 or x = - 7

Length always have positive value.

Therefore, Length of one side (dimension) of given rectangle = x = 3 cm; then

Length of second side (dimension) of given rectangle = x + 4 = 3 + 4 = 7 cm Answer

Check:

Formula for Area of rectangle = L X W

Put values of sides

Area of rectangle = 3 X 7

Area of rectangle = 21 square cm .. Proved