Question

what is wrong with this?
Let a and b be equal non-zero quantities
a = b
Multiply through by a
a^2 = ab
Subtract b^2
a^2 - b^2 = ab - b^2
Factor both sides
(a - b)(a + b) = b(a - b)
Divide out (a - b)
a + b = b
Observing that a = b
b + b = b
Combine like terms on the left
2b = b
Divide by the non-zero b
2 = 1

Answer 1

after subract by b^2 step is wrong
because on both sides you get zero
and then you multiply by something which still gives you zero and then remove the constant terms off
like 0=0
0x4=0x5
and then you cut the zeros off
therefor 4=5
that is absolutely wrong

Answer 2

hence from( factor both sides ) it is wrong

Answer 3

thanks :)

Answer 4

my pleasure!