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# HELP- Factorising Polynomials watch

1. 3x^3 - 2x^2 - 147x + 98 = (ax - c) (bx + d) (bx -d) where a, b, c and d are positive integers.
Work out the values of a, b, c and d.

Please could someone explain this to me? Its non-calculator, just unsure of how to do it; I assumed it was factor theorem but...
Thanks!
2. (Original post by nm1276)
3x^3 - 2x^2 - 147x + 98 = (ax - c) (bx + d) (bx -d) where a, b, c and d are positive integers.
Work out the values of a, b, c and d.

Please could someone explain this to me? Its non-calculator, just unsure of how to do it; I assumed it was factor theorem but...
Thanks!
It is. Compare coefficients.

to make the x³ terms on the left look at the right and see that we must multiply ax bx and bx to get x³

so

3x³=axbxbx
3x³=ab²x³
3=ab²

looks like you'll have to do this for the other x terms too so you can solve it.

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Updated: January 8, 2017
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