Question 1185806
<pre>
{{{(2x-a)^3 = 8x^3 - bx^2 + expr(3/2)bx - a^3}}}

That must be true for all values of x, so let's let x = a/2 to
make the left side zero.

{{{(2(a/2)-a^"")^3 = 8(a/2)^3 - b(a/2)^2 + expr(3/2)b(a/2) - a^3}}}

{{{(a-a)^3 = 8(a^3/8^"") - b(a^2/4^"") + 3ab/4 - a^3}}}

{{{(0)^3 = a^3 - ba^2/4^"" + 3ab/4 - a^3}}}

{{{0 =  - ba^2/4 + 3ab/4 }}}

Multiply through by 4

{{{0 =  - ba^2 + 3ab }}}

{{{ba^2=3ab}}}

Divide both sides by ab

{{{a=3}}} and b can be any non-zero number.

Edwin</pre>