a straight line passing through points (1,-2) is tangent of the parabola y=x^2, find the equation of the straight line.

and also what is meant by the term 'linear factors'? please explain it in general and in terms of 12x^2 + 7x - 12

and also explain how this works y = 2(2-x)^2 + 3 i got up to: -2(x-2)^2 + 3

the book however sketched the graph without it being negative.

Thanks alot