Algebra

Every item in the first term is multiplied with every item in the second term. 

Pick out the items that, when multiplied, result in an "x" coefficient product.  

(x³ + x² + x + 1) • (x⁴ – 8x³ + 17x² – 23x + 14)     gives you + 14x    

(x³ + x² + x + 1) • (x⁴ – 8x³ + 17x² – 23x + 14)     gives you – 23x    

add them together for the final value                                     – 9x    

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