(2x-5)²+(3x-7)(3x+7)+20x= 4x²-20x+25+(3x-7).(3x+7)+20x
=4x²-20x+25+9x²-49+20x= 4x²+25+9x²-49+13x²+25-49=13x²-24
(2x-5)²+(3x-7)(3x+7)+20x= 4x²-20x+25+(3x-7).(3x+7)+20x
=4x²-20x+25+9x²-49+20x= 4x²+25+9x²-49+13x²+25-49=13x²-24