Question 1143149
{{{ s = 4x + 7 }}}
The square of the side = the area of the square
{{{ s^2 = ( 4x + 7 )^2 }}}
{{{ s^2 = 16x^2 + 56x + 49 }}}
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proof:
Say {{{ x = 1/4 }}}
{{{ s = 4*(1/4) + 7 }}}
{{{ s = 8 }}}
{{{ s^2 = 64 }}}
and
{{{ s^2 = 16*(1/4)^2 + 56*(1/4) + 49 }}}
{{{ s^2 = 1 + 14 + 49 }}}
{{{ s^2 = 64 }}}
OK