Question 464404

{{{8x^2-10xy-25y^2}}}.....replace {{{-10xy}}} with {{{10xy-20xy}}}

{{{8x^2+10xy-20xy-25y^2}}}.....group first and third,  second and fourth terms

{{{(8x^2-20xy)+(10xy-25y^2)}}}.......factor out {{{4x}}} from first group and {{{5y}}} from second group

{{{4x(2x-5y)-5y(2x-5y)}}}

{{{(2x-5y) (4x+5y)}}}