Question 357963
Use the FOIL Method,
{{{(5-2x^7)^2= (5-2x^7)(5-2x^7)}}}
{{{(5-2x^7)^2= 25-5(2x^7)-2x^7(5)+4x^14}}}

{{{highlight((5-2x^7)^2=4x^14-20x^7+25)}}}