<p>What Should be subtracted and added to the expression &nbsp;<span class="math-editor mathquill-rendered-math"><span class="roman font"><var>x</var></span><sup class="non-leaf">4</sup><span class="binary-operator">&minus;</span>4<var>x</var>&sup3;<span class="binary-operator">+</span>10<var>x</var><span class="binary-operator">+</span>7</span>&nbsp; so that the expression is made perfect square.</p>