Question 1128140
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<pre>
Area = {{{pi*r^2}}} = {{{pi*(16x^2 -40x+25)}}} = {{{pi*(4x-5)^2}}}  ====>


{{{r^2}}} = {{{(4x-5)^2}}}  ====>  r = |4x-5|  ====>  the diameter = 2r = 2*|4x-5|    <U>ANSWER</U>.
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Solved.