For what value of $a, (x - 5)$ is a factor of $x^3 - 3x^2 + ax - 10$?
Given:
Given expression is $x^3-3x^2+ax-10$.
$x - 5$ is a factor of $x^3-3x^2+ax-10$.
To do:
We have to find the value of $a$.
Solution:
We know that,
If $(x-m)$ is a root of $f(x)$ then $f(m)=0$.
Therefore,
$f(5)=0$
$\Rightarrow (5)^3-3(5)^2+a(5)-10=0$
$\Rightarrow 125-75+5a-10=0$
$\Rightarrow 5a+40=0$
$\Rightarrow 5a=-40$
$\Rightarrow a=\frac{-40}{5}=-8$
The value of $a$ is $-8$.
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