Q3 of 47 Page 78

Find the value of m if x3 – 6x2 + mx + 60 leaves the remainder 2 when divided by (x + 2).

x3 – 6x2 + mx + 60 divided by (x + 2) and remainder = 2


Remainder theorem states that if p(x) is any polynomial and a is any real number and If p(x) is divided by the linear polynomial (x – a) , then the remainder is p(a).


Let p(x) = x3 – 6x2 + mx + 60 and we have (x + 2)


The zero of (x + 2) is –2


Now using Remainder theorem,


p(x) = x3 – 6x2 + mx + 60 is divided by x + 2 then, p(–2) is the remainder which is 2


p(–2) = x3 – 6x2 + mx + 60 = 2


= (–2)3 – 6(–2)2 + m(–2) + 60 =2


= – 8 – 24 – 2m + 60 = 2


= – 32 – 2m + 60 = 2


= 28 – 2m = 2


= 2m = 28 – 2


= 2m = 26


m = 13


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