Question

Find the value of :

$4x^3-5x^2-6x+7$ when $x=3$

Answer 1

Substituting $x=3$ in the given expression , we get

Here $4x^3-5x^2-6x+7$ can be written as $4\times x\times x\times x-5\times x\times x-6\times x+7$

$\begin{array}{rcl}4x^3-5x^2-6x+7& =& 4\times x\times x\times x-5\times x\times x-6\times x+7\\ & =& 4\times 3\times 3\times 3-5\times 3\times 3-6\times 3+7\\ & =& 108-45-18+7\\ & =& 115-63\\ & =& 52\end{array}$

Hence,the value of given expression will be $52$