Question 1127975
{{{ V = 690 }}} cm3
Let {{{ x }}} cm = the width of the open box
{{{ x + 8 }}} cm = the length of the open box
{{{ 2 }}} cm = the height of the open box
{{{ 2x*( x + 8 ) = 690 }}}
{{{ x^2 + 8x = 345 }}}
complete the square
{{{ x^2 + 8x + 16 = 345 + 16 }}}
{{{ ( x + 4 )^2 = 361 }}}
{{{ x + 4 = 19 }}}
{{{ x = 15 }}}
and
{{{ x + 8 = 23 }}}
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The dimensions are 15 cm x 23 cm x 2 cm
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check:
{{{ 2*15*23 = 690 }}}
{{{ 690 = 690 }}}
OK