i am edditing my post because i got the answer wrong
<h3>f(x)=3x³-13x²-3x+45</h3><h3>f(x)=3x³-9x²-4x²+12x-15x+45</h3><h3>f(x)=3x²(x-3)-4x(x-3)-15(x-3)</h3><h3>f(x)=(x-3)(3x²-4x-15)</h3><h3>f(x)=(x-3)(x-3)(3x+5)</h3><h2>f(x)=(x-3)²(3x+5)</h2>
<h3><u>Roots:</u></h3><h3>x=3</h3><h3>x=-5/3</h3>
Here's the right way:


Here's the way they want you to do it:



6 :)
no. of books: 1 2 3 4
combinations: 12, 13, 14, 23, 24, and 34