Question

If $x=-1$, $y=2$and $z=-2$ , then find the value of the following:

$xyz+9x^{2}z-3y{z}^2+10x{y}^2-2$

Answer 1

Finding the value of expression

The given algebraic expression is $xyz+9x^{2}z-3y{z}^2+10x{y}^2-2$

According to the question,

Putting the value of $x=-1$, $y=2$and $z=-2$

we have,

$\begin{array}{rcl}xyz+9x^{2}z-3y{z}^2+10x{y}^2-2& =& (-1)\times 2\times (-2)+9\times {(-1)}^2\times (-2)-3\times 2\times {(-2)}^2+10\times (-1)\times 2^2-2\\ & =& 4+9\times (-2)-6\times 4-10\times 4-2\\ & =& 4-18-24-40-2\\ & =& 4-84\\ & =& -80\end{array}$

Hence, the value of the expression $xyz+9x^{2}z-3y{z}^2+10x{y}^2-2$ at $x=-1$, $y=2$ and $z=-2$ is $-80$