Question 257988

<pre><font size = 4 color = "indigo"><b>
Let the number be x

The other tutor's solution is incorrect because he did the no-no
of dividing an equation through by the variable x.  When you do that
you lose a solution.  He lost the solution 0. His no-no was as bad
if not worse than your misspelling "grateful".  <font face = "wingdings" size = 7 color = "red">J</font>


x squared equals x times four

{{{x^2=x*4}}}

{{{x^2=4x}}}

{{{x^2-4x=0}}}

{{{x(x-4)=0}}}

Use the zero factor principle:

Setting the first factor {{{x}}} equal 0 gives

{{{x=0}}}

Setting the second factor {{{(x-4)}}} equal to 0 gives:

{{{x-4=0}}}
{{{x=4}}}

So the number could be 0 or 4.

Edwin</pre>