Question 897660
(1) 
{{{ 4x^2 = 12x }}}
{{{ 4x^2 - 12x = 0 }}}
{{{ 4x*( x - 3 ) = 0 }}}
For this to be true, either
{{{ x = 0 }}} or {{{ x = 3 }}}
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(2) 
{{{ 6x^2 = 6x }}}
{{{ 6x^2 - 6x = 0 }}}
{{{ 6x*( x - 1 ) = 0 }}}
{{{ x = 0 }}} and
{{{ x = 1 }}}
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(3)
{{{ 3x^2 + 6 = 2x^2 + 18 }}}
Subtract {{{ 2x^2 }}} from both sides
{{{ x^2 + 6 = 18 }}}
Subtract {{{ 6 }}} from both sides
{{{ x^2 = 12 }}}
{{{ x = sqrt(12) }}}
{{{ x = 2*sqrt(3) }}}
and, also
{{{ x = -sqrt(12) }}}
{{{ x = -2*sqrt(3) }}}