Question

Find the lengths of the sides a) Area = 21 cm2​

Answer 1

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

Answer 2

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

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