Question

A garden measuring 12 meters by 6 meters is going to have a walkway constructed all around the perimeter, increasing the total area to 160 square meters. What will be the width of the pathway? (The pathway will be the same width around the entire garden).

Answer 1

2

Explanation:

Original width = 6

New width = 6 + x + x = 6 + 2x

Orignal length = 12

New length = 12 + x + x = 12 + 2x

A = l * w

160 = (6 + 2x)(12 + 2x)

160 = 2(3+x) * 2(6+x)

160 = 4 * (3 + x)(6 + x)

160/4 = (3 + x)(6 + x)

40 = 18 + 6x + 3x + x^2

40 = 18 + 9x + x^2

x^2 + 9x - 22 = 0

= x^2 + 11x - 2x - 22 = 0

= x(x + 11) - 2(x + 11) = 0

= (x + 11) (x - 2) = 0

x = - 11, 2

Since we cannot have a negative width because it's a dimension,

x = 2 is right

Answer 2

x=2

Explanation:

Original width = 6

New width 6+x+x

Orignal length 12

New length 12+x+x

A = l*w

160 = ( 6+2x) ( 12+2x)

Factor

160 = 2( 3+x) 2(6+x)

Divide each side by 4

40 = (3+x) (6+x)

FOIL

40 = 18+ 6x+3x+ x^2

40 = 18 +9x+x^2

Subtract 40 from each side

0 = x^2 +9x -22

Factor

0 = (x +11) (x-2)

Using the zero product property

x +11 =0 x-2 =0

x= -11 x=2

Since we cannot have a negative sidewalk

x =2