Anyone remember that math equation by adding and subtracting numbers that come to an illogical answer???

Question

Starts out with simple numbers up to 20 I think and when all equations solved it doesn't make mathematical sense....HELP

Answer 1

There are also many simple algebraic "proofs" that 1=0 or 1=2. They normally contain a concealed division by zero. Some examples instead use squares and square roots to achieve the same end (by putting the square root of x^2 equal to x rather than |x|; when x is negative this is incorrect)

Answer 2

There is more than one equation where the answers make sense mathematically, but then don't work when you have to plug them back into the original equation. They are called extraneous solutions.