



 
Hi Ma, Since (x + 3) is a factor of x^{3} + Ax^{2} + Bx + 12 there is a polynomial g(x) so that
Notice that when x = 3 the right side is zero so
This is a linear equation in the variables A and B. Use the fact that (x  2) is a factor of x^{3} + Ax^{2} + Bx + 12 to find a second linear equation is A ab\nd B and then solve these two equation for A and B. I hope this helps,  


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