A rectangle’s length is 3 cm more than its width. Find the dimensions of the rectangle if its area is 20 cm2.?

Attachment image

3 Answers

Relevance
  • Favourite answer

    x * (x + 3) = 20

    x^2 + 3x = 20

    x^2 + 3x + 1.5^2 = 20 + 1.5^2

    (x + 1.5)^2 = 20 + 2.25

    (x + 1.5)^2 = 22.25

    (1/4) * (2x + 3)^2 = (1/4) * 89

    (2x + 3)^2 = 89

    2x + 3 = +/- sqrt(89)

    2x = -3 +/- sqrt(89)

    x > 0

    2x = (sqrt(89) - 3)

    x = (sqrt(89) - 3) / 2

  • David
    Lv 7
    2 months ago

    Let its length be x+3 and its width be x

    Area of rectangle (x+3)*x = 20 or x^2 +3x -20 = 0

    Solving the quadratic equation x = +3.216990566 

    Therefore: length = 6.216990566 cm and width = 3.21699056 cm 

    Check: 6.216990566*3.216990566 = 20 square cm

  • 2 months ago

    x(x + ) = 20 

    x^2 + 3x  = 20 

    Complete the Square 

    (x + 3/2)^2 - ( 3/2)^2 = 20 

    (x+ 3/2)^2 - 9/4 = 20 

    (x + 3/2)^2 = 20  + 9/4 = 89/4 

    Square root both sides 

    x + 3/2 = +/-sqrt(89) / 2 

    x = - 3/2 +/- sqrt(89) / 2 

    x = - 3/2 +/- 9.4339.... / 2 

    x = 6.4339... / 2 

    x = 3.2169... 

    & x + 3 = 6.2139.... 

Still have questions? Get answers by asking now.