assume the
contrary:
2
.5 =
p/
q
square both lines.
2 =
p2/
q2
multiply both sides by
q2
2
q2 =
p2
p2 must be even, for it is equal twice the value of an integer. (
q2 )
p is therefore
even as well, for if the square of a number is even, the number is as well.
because
p is even, it can be written as 2m, where m is some other
whole number. placed into the equation, it reads:
2
q2 = (2
m)
2 = 4
m2
divide both sides by 2.
q2 = 2
m2
with the same arguments used previously, q must also be even, and may be represented as 2n. same steps, resulting in
2
.5 =
p/
q = 2
m/2
n
lose the 2s.
2
.5 =
m/
n
This
process can continue indefinitely, meaning the fraction is
infinitely reducable. A quality of a fraction is that it may be represented as a ratio between two
relatively prime integers. (like 10/20 can be reduced to 5/10, and finally to 1/2)
yeah...
QED