if x=3, then f(x)=0, so put in x=3 into f(x)=0 and solve for b.
Now that you know b, you can divide out the factor (x-2) and are left with a quadratic 3x^2+ ... which if =0, then you can factor or use the quadratic equation to find those two roots.
If (x-3) is a factor of 3x^3+bx^2-17x-12.
a. Find the value of b.
b.Hence , find the roots fo the equation 3x^3+bx^2-17x-12=0.
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