Question 248100
A rectangular lawn measuring 8m by 4m is surrounded by a flower bed of uniform width.
 The combined area of the lawn and the flower bed is 165m^2. What is the width of the flower
:
Let x = the width of flower bed
:
Then the overall dimensions (flower bed & lawn) will be:
(2x + 8) by (2x + 4)
:
Overall area
(2x+8)*(2x+4) = 165
FOIL
4x^2 + 8x + 16x + 32 = 165
A quadratic equation
4x^2 + 24x + 32 - 165 = 0
4x^2 + 24x - 132 = 0
Simplify, divide by 4, results:
x^2 + 6x - 33 = 0
Use the quadratic formula to solve this
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}
In this problem: a=1; b=6; c=-33
{{{x = (-6 +- sqrt( 6^2-4*1*-33 ))/(2*1) }}}
Do the math here and you should get a positive solutions of:
x ~ 3.48 meters is the width of the flower bed
;
:
Check on a calc: enter (2(3.48)+8)*(2(3.48)+4) = 164 ~ 165