Question

Marco states that both expressions are equal to x. Do you agree or disagree with Marco? Explain your thinking. 8x-7x -5x+5x

Answer 1

We diagree with Marco because

$8x-7x=x$

and

$-5x+5x=0$

where, in the first expression, we factorized x and got

$8x-7x=(8-7)x=1x=x$

and in the second one, we got

$(-5+5)x=0\cdot x=0$

In summary, the first expression is equal to x and the second one is equal to zero, so they are different expressions.