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If mx^3+(n-5)x^2+3x-1 is divided by (x-2) , the remainder is -11 and it has a factor of (x-1), find the values of m and n.

 Oct 15, 2015
 #1
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If mx^3+(n-5)x^2+3x-1 is divided by (x-2) , the remainder is -11 and it has a factor of (x-1), find the values of m and n

 

If x - 1 is a factor, then 1 is a root.....and we have.....

 

m + n - 5 + 3 - 1  = 0     simplify

 

m + n  - 3 = 0    →   n = 3 - m

 

And we know that  f(2) = 11   .....so....

 

m(2)^3 + ( 3 - m -  5)(2)^2  + 3(2) - 1 = 11   simplify

 

8m  + (-2 - m)(4)  + 6  - 1   = 11

 

8m -8 - 4m  + 6 - 1   = 11

 

4m - 3 = 11      →  m  = 7/2      and  n = 3 - 7/2 =  -1/2

 

Here's a graph of the function :    https://www.desmos.com/calculator/vsp5mk19bj

 

 

 

cool cool cool

 Oct 15, 2015

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