Question 550665
{{{ (3r+8)^2 }}}
{{{ 9r^2 + 24r + 24r + 64 }}}
{{{ 9r^2 + 48r + 64 }}} answer
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There's a very simple way to check this
Pick a small prime number like 13
and say {{{ r = 13 }}}
{{{ ( 3r + 8 )^2 = ( 39 + 8 )^2 }}}
{{{ 47^2 = 2209 }}}
and
{{{ 9r^2 + 48r + 64 = 9*13^2 + 48*13 + 64 }}}
{{{ 1521 + 624 + 64 = 2209 }}}
OK