I'm not quite sure if this is the answer because I don't know what math you're in but if you use elimination instead of substitution, you cancel out the y and so you're left with 0=x^2 + 2x. this is a positive 2x because you multiply the whole equation by negative one so the y can cancel out. with this new equation you can factor. both terms have an x so now it's : 0=x(x+2). if you multiply this back out you will end up with 0=x^2+2x. then you set the parenthesis to zero: 0=x+2 and solve. therefore x= -2. and then you set x to zero : 0=x. so x has two answers: 0 and -2
