Originally Posted by
push1t
since 3x^2-5x^2 simplifies into -2x^2, you're left with -2x^2+2. it will be the form (-2x__)(x__) to fill in the blank spaces you need two number that multiply to form 2 yet add to form zero in this expression. it has to be 2 and 1. since -2*1 gives -2 and 2*1 gives 2, -2+2 gives zero, yet 2*1 gives 2. so the expression is (-2x+2)(x+1). The reason you need zero is because you assume the quadratic form ax^2 +bx +c, in the expression you gave a would be -2 b would be zero and c would be +2