## Posts Tagged ‘algebra’

There’s a question I like to ask random people: where is the flaw in the argument that $-1 = 1$ because $0*(-1)=0*1$? I very rarely get a satisfactory response. Usually the answer is that “you’re not allowed to multiply both sides by zero.” But we can come up with a slightly subtler argument: $-1 = 1$ because $(-1)^2 = 1^2$. Some just don’t answer, other will insist that its not allowed… To me it suggests something is deeply wrong with how most people understand algebra.