Expand the right side:
[tex](ax-c)(bx+d)(bx-d)=(ax-c)(b^2x^2-d^2)[/tex]
[tex]=ab^2x^3-b^2cx^2-ad^2x+cd^2[/tex]
Notice that 98 = 2 * 7 * 7, so we have [tex]c=2[/tex] and [tex]d=7[/tex].
Then
[tex]-ad^2=-147\implies a=\dfrac{147}{49}=3[/tex]
and
[tex]ab^2=3\implies b^2=1\implies b=1[/tex]
