Past Papers’ Solutions | Cambridge International Examinations (CIE) | AS & A level | Mathematics 9709 | Pure Mathematics 2 (P2-9709/02) | Year 2010 | Oct-Nov | (P2-9709/22) | Q#7

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Question

The polynomial , where  and  are constants, is denoted by . It is given that   is a factor of , and that when  is divided by  the remainder is 10.


i.      
Find the values of a and b.

   ii.       When a and b have these values, solve the equation p(x)=0.

Solution

     i.
 

We are given that;

We are also given that is a factor of .

When a polynomial, , is divided by , and  is factor of , then the remainder is ZERO i.e. .

We can write factor in standard form as;

Therefore;

We are also given that when is divided by the remainder is 10.

When a polynomial, , is divided by , the remainder is the constant

We can write divisor in standard form as;

Therefore;

From we can substitute in above equation ;

Substitution of in any of these two equations yields value of . We choose;

   ii.
 

We are required to solve .

We are given that;

We have found in (i) that and  therefore;

We are also given that is factor of .

When a polynomial, , is divided by , and  is factor of , then the remainder is ZERO i.e. .

Therefore, division of with  factor will yield a quadratic factor with ZERO remainder.

We divide  by .

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Therefore;

Since we are given that;

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