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2. Polynomials
hard
Find the remainder when $x^{3}+3 x^{2}+3 x+1$ is divided by $x-\frac{1}{2}$
A
$-\frac{27}{8}$
B
$\frac{27}{8}$
C
$7$
D
$8$
Solution
$\because$ The zero of $x-\frac{1}{2}$ is $\frac{1}{2}$ $\left[\because x -\frac{1}{2}=0 \Rightarrow x =\frac{1}{2}\right]$
and $p ( x )= x ^{3}+3 x ^{2}+3 x +1$
$\therefore $ For divisor $= x -\frac{1}{2},$ remainder is given as
$p \left(\frac{1}{2}\right)=\left(\frac{1}{2}\right)^{3}+3\left(\frac{1}{2}\right)^{2}+3\left(\frac{1}{2}\right)+1=\frac{1}{8}+\frac{3}{4}+\frac{3}{2}+1$
$=\frac{1+6+12+8}{8}=\frac{27}{8}$
Thus, the required remainder $=\frac{27}{8}$.
Standard 9
Mathematics