Question

3（x+5)^2-2(x-3)^2-(x-9)(x+9)=81

Answer 1

3（x+5)^2-2(x-3)^2-(x-9)(x+9)=81

3(x^2+25+10x)-2(x^2+9-6x)-(x^2-81)=81

3x^2+75+30x-2x^2-18+12x-x^2+81=81

42x+57=0

x=-19/14