Sunday, 1 December 2019

Does Polynomial Remainder Theorem work with divisors that are quadratic?



The Polynomial Remainder Theorem states that the remainder of the division of a polynomial f(x) by a linear polynomial xr is equal to f(r). In particular, xr divides f(x)f(r)=0



But what if the divisor is not linear and of a degree higher than one?



Consider this question:





Let P(x) be any polynomial. When it is divided by (x13) and (x17), then the remainders are 15 and 35 respectively. The remainder, when P(x) is divided by (x13)(x17), is




How I approached it:



P(13)=15
P(17)=35




But how do I figure out the remainder if the degree of the divisor is greater than one?


Answer



Alternative hint:
P(x)=g(x)(x13)(x17)+ax+b
for some  a  and  b . Your recovered values of  P(13)=15  and  P(17)=35  give you two linear equations to solve for a  and  b .


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