You must know this for your HSC Mr Brightside.
Let us understand where this actually comes from.
If we have quadratic family of and we will let this be equivalent to each other such that, the roots are
and
Dividing through by
By equating coefficients,
That is to say,
The sum of the roots of the quadratic in that form is,
The product of the roots of the quadratic in that form is,
Let us apply this,
For consecutive roots, we can right this as the quadratic having roots,
Now, applying the formula we just created.
The sum of the roots:
The produce of the roots are:
We can now solve for
From
Off it goes into
Solve and find