Question

The width of a rectangle is 15 cm less than 3 times the length. If the area is 42 square cm.Find the dimensions of the rectangle.

Answer 1

Step-by-step explanation:

let length be x

bredth= (3*x)-15

area = l*b

42=(3x-15)*x

42=3x²-15x

3x²-15x-42=0

x²-5x-14=0

x²-7x+2x-14=0

x(x-7)+2(x-7)=0

(x+2)(x-7)=0

x=-2,x=7

x must be 7 because length can't be negative.

lenght = 7 cm

bredth= (3*7)-15

= 21-15

= 6 cm