Question 1209875
<pre>
Fill in the blanks with constants, to make a true equation:

\frac{x^2 - 6x - 3}{x^3 - 4x} = ___/x + ___/(x - 2) + ___/(x + 2) 

{{{(x^2 - 6x - 3)/(x^3 - 4x)}}} = {{{"___"/x + "___"/(x - 2) + "___"/(x + 2)}}}
{{{(x^2 - 6x - 3)/x(x^2 - 4)}}} = {{{"___"/x + "___"/(x - 2) + "___"/(x + 2)}}}
{{{(x^2 - 6x - 3)/x(x - 2)(x + 2)}}} = {{{"___"/x + "___"/(x - 2) + "___"/(x + 2)}}}
{{{(x^2 - 6x - 3)/x(x - 2)(x + 2)}}} = {{{A/x + B/(x - 2) + C/(x + 2)}}}
{{{matrix(1,3, x^2 - 6x - 3, "=", A(x - 2)(x + 2) + B(x)(x + 2) + C(x)(x - 2))}}} ---- Multiplying by LCD, x(x - 2)(x + 2)
{{{matrix(1,3, x^2 - 6x - 3, "=", A(x^2 - 4) + B(x^2 + 2x) + C(x^2 - 2x))}}} 
{{{matrix(1,3, x^2 - 6x - 3, "=", Ax^2 - 4A + Bx^2 + 2Bx + Cx^2 - 2Cx)}}} 
{{{matrix(1,3, x^2 - 6x - 3, "=", Ax^2 + Bx^2 + Cx^2 + 2Bx - 2Cx - 4A)}}} 
{{{matrix(1,3, x^2 - 6x - 3, "=", (A + B + C)x^2 + (2B - 2C)x - 4A)}}}

<font color = blue><font size = 4><b>(1)</font></font></b><font color = red><font size = 4><b>x^2</font></font></b> <font color = green><font size = 4><b>(- 6)</font></font></b><font color = red><font size = 4><b>x </font></font></b><font color = magenta><font size = 4><b>(- 3)</font></font></b> = <font color = blue><font size = 4><b>(A + B + C)</font></font></b><font color = red><font size = 4><b>x^2 </font></font></b><font color = green><font size = 4><b>(2B - 2C)</font></font></b><font color = red><font size = 4><b>x</font></font></b><font color = magenta><font size = 4><b> (- 4A)</font></font></b>

{{{system(matrix(3,1, matrix(1,6, 1, "=", A + B + C, "------", eq, "(i)"), matrix(1,6, - 6, "=", 2B - 2C, "------", eq, "(ii)"), matrix(1,6, - 3, "=", - 4A, "---------", eq, "(iii)")))}}} ----- EQUATING left-terms coefficients to right-terms coefficients

  </b><font color = red><font size = 4><b>- 3 = - 4A</font></font></b> ---- eq (iii)
  {{{(- 3)/(- 4) = highlight(3/4 = A)}}}

    </b><font color = red><font size = 4><b>1 = A + B + C</font></font></b> -- eq (i)
    {{{matrix(2,1, 1 = 3/4 + B + C, 1 - 3/4 = B + C)}}} ------ Substituting {{{3/4}}} for A 
    {{{1/4 = B + C}}} ----- eq (iv)

  </b><font color = red><font size = 4><b>- 6 = 2B - 2C</font></font></b> ---- eq (ii)
2(- 3) = 2(B - C)
   - 3 = B - C ----- eq (v)

 {{{- 2&3/4 = 2B}}} ----- Adding eqs (iv) & (iv)
 {{{matrix(2,1, - 11/4 = 2B, - 11 = 8B)}}}
{{{highlight(- 11/8 = B))}}} 

     {{{1/4 = B + C}}} ----- eq (iv)
     {{{1/4 = - 11/8 + C}}} -- Substituting {{{- 11/8}}} for B in eq (iv)
 {{{matrix(3,1, 11/8 + 1/4 = C, 11/8 + 2/8 = C, highlight(13/8 = C))}}}

{{{(x^2 - 6x - 3)/x(x - 2)(x + 2)}}} = {{{"___"/x + "___"/(x - 2) + "___"/(x + 2)}}} now becomes: {{{(x^2 - 6x - 3)/x(x - 2)(x + 2)}}} = {{{highlight(highlight_green(highlight((3/4)/x - (11/8)/(x - 2) + (13/8)/(x + 2))))}}}</pre>