Question 184171
If the sides of a square are lengthened by 8cm, the area becomes 144 cm^2.
 Find the length of a side of the original square.
;
Let x = side of the original square
then
(x+8) = side of the larger square
:
(x+8)^2 = 144
Find the square root of both sides
x + 8 = 12
:
x = 12 - 8
:
x = 4 cm is the length of the original square
:
:
Check: (4+8)^2 = 144
:
:
If you absolutely have to have a quadratic equation:
Foil (x+8)^2
x^2 + 16x + 64 = 144
x^2 + 16x + 64 - 144 = 0
x^2 + 16x - 80 = 0
Factor
(x+20)(x-4) = 0
Positive solution is what we want:
x = 4 cm